Pre-Development[]
After the success of Paper Mario Drawing of Disaster, Gear Games had become a trusted developer of the Paper Mario series, and will be called if Nintendo will greenlight another Paper Mario project that is much closer to the spirit of the classic era.
However, the director of the previous game, Samtendo09 (t∣b∣c), felt that his team shouldn't keep the Drawing Cards mechanic for the sequel as despite managing to be proven more fun to use than the Stickers from Sticker Stars and the Battle Cards from Color Splash. Part of this is because to avoid staleness, and another is to allow the potential sequel to allow more strategy. Because of that, the Things and similar successors will not be used as major part of the game mechanic in favor of the lesser Summon Cards, which summon various Mario characters for a special attack or support.
Although Shigeru Miyamoto isn't too enthusiastic with the fairly decreased focus on the mainline Mario characters, he eventually realizes that the increased NPC variation is seen as a vast improvement compared to the original version of Sticker Star and Color Splash, which are criticized for boring character cast, especially toward the Toads. As such, he let Gear Games to allow further new adventures, so long that the presence of the mainline characters will not be too minimal.
He did add a recommendation for a potential Paper Mario sequel, and it is to the fact that if they want to continue the classic Paper Mario gameplay, then Gear Games do need to make some adjustment to stand out from Drawing of Disaster. Samtendo even admitted that they need at least a replacement for the Drawing Cards that works differently and that, while having not as much impact as the predecessors, will allow more strategies toward enemies and bosses, thus more replayability.
Priority[]
Indeed, increasing the replay value than even Drawing of Disaster is one of Gear Games' priority, as it will allow the players to come back and experiment on the game. The first step is, since it will use the same battle engine from Drawing of Disaster but with some modifications, to determine how much they can pull out of a party of four.
Gear Games did realized that trying to make twenty partners in just one base game will go nowhere, does to the potential quality problem for each partner. However, they figured one thing that no prior Paper Mario games, be it by Intelligent Systems or by other developer teams, had ever done before. The idea will be bringing back past partners with the new idea of Partner Cards.
At first they would go for fan favorites and then some, but they felt that each Partner have their own share of fans and felt that it is not fair that only fan favorites can stay. As a result, they went as far as including every single Partners from the IS-produced Paper Mario games. They couldn't include the Pixls from Super Paper Mario does to their ability being one-noted and difficult to work around with, unlike Kersti and Huey.
However, Gear Games decided to be more ambitious and included Partners from several other Paper Mario games produced by developer teams other than IS, as well as the Recut version of Sticker Star and Color Splash. It explains why Kersti's characterization is closer to the Recut version. They also contacted the other development teams such as Pyro Enterprises for permission to use of their Partners and other affiliated characters.
Discretion About Sticker Star and Color Splash[]
However, the inclusion of the Recut-only Partners caused Miyamoto to give them a recommendation that if they are going to use the Recut partners, then the events of the original versions of Sticker Star and Color Splash should not be fully mentioned in any way. It had to do with Miyamoto finding the final version of Sticker Star as "boring".
The final step for the Partner Cards is to justify their existence. Since they are not "out of nowhere" like Things and will not involve a "fairy companion", Gear Games decided to have the villain to be responsible for the creation and imprisoned all of the Partners that is included in their final list.
Villain Selection[]
Initially, Bowser was suggested, but then there is consideration that, in addition that Bowser has been already a mainline antagonist (for both Super Mario mainline series and Yoshi franchise) and is consistently so, they felt that giving him the main villain role again like in Sticker Star and Color Splash would be already redundant. They quickly noticed that since they included all of the Partners from the available "sets", they can use a lesser known mainline nemesis instead.
One employee also suggested Dimentio, but the idea is turned down as according to Samtendo himself, Dimentio's debut and his role as the final boss and the enigmatic true culprit will greatly worn down his appeal, and thus relegated as a Partner Card. This is because Dimentio was a Partner back in The Rise of Shadow.
Eventually, the final decision goes for Wario, of all people, although not without constructing his backstory prior to his villainy first, albeit in subtle details. After that, the development for the gameplay and the story had begin.
That being said, remnant of the previous idea, which is about Dimentio being originally one of the possible villains, is also found in the final version. Dimentio did in fact originally planned to have revenge on Mario and everyone of his allies, and attempted to convince Wario to team up (and double-cross him later on), only for Wario to immediately attack him out of distrust since "[Wario] was double-crossed by another clown before". This is to also help establish that Wario is significantly tougher than usual, since Dimentio himself is powerful.
Characters[]
For the Partners, aside of the returning Partners, most of the new ones will be different species that aren't frequently used for Partners in Paper Mario games made by other developing teams. Lashie the Yoshi and Gigan T the Giant Toad are exceptions, does to liking to explore and are allies in their respective debut prior to Stolen Worlds (although they are not playable). That said, Gigan T's size is scaled down for battles.
For the rest, the team come up with a Magikoopa (Kamenia), a Banderino (Robino), a Galoomba who originally to be a normal Galoomba before becoming a Para-Galoomba (Officer Gale), a Dry Bones (Detective Drebs), a Pionpi (Pinkon), a new species called the Sertincant (Serville), a Skeleton Bee (Skelt) and a Pencillier (Pennnsil). They were also given different and distinct clothing, and in a case of several of them, an occupation.
There were also species considered, such as a Chain Chomp, a Moe-Eye and a Spike, but felt that the team should go for less known species instead in order to surprise fans. That being said, the design for the Moe-Eye is eventually given for a photo-taker Moe-Eye NPC in the Ancient World.
Wario's Starring Antagonism[]
The reason why Wario is chosen as the main antagonist is does to multiple reasons that will be stated as below.
As a celebration about Paper Mario in general, the director of the game, Samtendo09 (t∣b∣c), felt that a long time nemesis will fit more than a new villain without resorting into using Bowser again. The other candidate was Tatanga, but Wario eventually become better established as one as the following reasons explains it further.
Most of Mario's Partners are people that he had become friends with and maintained the healthy relationship, while Wario have little to no permanent allies throughout his adventures, and Samtendo didn't counted Waluigi as such does to the latter never appearing in any Nintendo-produced Wario Land and WarioWare games, putting question about the trust between the two.
Wario's rivalry with Mario, over the years, had become more of simple animosity than genuine rivalry compared to between Mario and Bowser, and although Wario is a straight up antagonist in Stolen World, Bowser yelled at Wario that there can only be one rival to Mario (Bowser himself) back in Paper Mario Drawing of Disaster during one of Bowser's intervals when Bowser noticed that Wario had gotten into Mario's way a few times, which only caused Wario to be more hostile toward Bowser in this game.
And finally, the constant failures (at least financial failures) started to negatively affected Wario worse than ever, and Wario acted a bit more maliciously than usual in WarioWare Gold, where the tournament engaged by Wario is only a trick so that the spectators and players pay their entries, and then attempted to go away with the falsely promised prize, making it possible that increasingly constant failures can make Wario acting more malicious than usual.
That said, Samtendo also wanted Wario to be a bigger threat instead of pity rivalry, which result Wario becoming a genuine villain since his earliest appearances (Super Mario Land 2: Six Golden Coins, Mario & Wario and Wario's Woods), although not without his more comical moments.
The toilet jokes involving Wario are also vastly toned down with only some throwaway jokes involving them, with Wario Waft being used only in battle and a risky one for Wario. Including much more toilet humors than those will result making Wario much more ridiculous as a villain in a bad way.
Although this is not the first time Wario turned back into the main antagonist (WarioWare Gold as mentioned before and Super Mario Maker D.I.Y.), it is the first time where Wario become genuinely vile does to his actions, instead of a greedy jerk or a disrespectful thief, respectively.
While Miyamoto and some other staffs found the idea of Wario being a main villain rather unexpected, see baffling for some, they do understood the reasons behind the idea and let it slide. They also understood that Waluigi's betrayal back in Drawing of Disaster also already negatively impacted Wario, thus allows for following this build up.
That being said, the current staff are aware that just using Wario will potentially make an outcry from those who prefer an original villain, as they already knew that Bowser had caused backlash back when he was a villain in Sticker Star and the original version of Color Splash.
As such, instead of focusing on only Wario as the main villain, the other villains working for him will also have a much more active role as well instead of being just bosses, allowing a joint league. This includes returning minor villains like the Koopa Bros.
The origin behind Wario's Rage Smash was based of an internal joke around his "Must rage nap!" moment from WarioWare Gold. Although the Rage Smash itself is extremely devastating, Samtendo reveals that he only performs it when he is about to reach a rage-induced breaking point, as in being far more upset and angrier than usual.
The Adrenaline Boost is conceptualized to ensure Wario become a bigger threat than he ever was, allowing him to outmatch the likes of strong villains like Bowser and Dimentio. The Adrenaline Boosts allows him to be immune to one-hit kill attacks, as well as brainwashing in any sort. This boost is eventually originated from some power orbs he stole from the Ancient World, but only the Ancient World's Merlon is aware of this fact.
Finally, since going for his usual plumber attire will not fit his newfound goal of planetary conquests, his new attire is more in-line of an actual emperor while still having nods of Wario's original plumber attire. This allows Wario to look mildly more menacing and to emphasize his upped greed.
"Bring Me Some-a Wicked Henchmen!"[]
Tatanga being brought back is does to Wario being back as a main villain, and also does to common theory about Wario using / hiring Tatanga to distract Mario while Wario takes over the Mario Land. Tatanga's appearance in Super Mario Realms who he goes traitorous against Wario does reinforce this, although the treachery is almost reversed in Stolen Worlds. The company feels that not using Tatanga with Wario going back into villainy would be a huge missed opportunity so they have him joining back with the greedy plumber (although with reluctance).
Likewise, Lord Crump returning as General Crump is does to the high-ranked member of the X-Nauts being launched away into space in Paper Mario: The Thousand-Year Door, and to likewise allowing him to have revenge on Mario after being found in Tatanga, who by himself is a space dweller, before (reluctantly) joining forces with Wario.
After having the three minor villains to return working for Wario (with various motivation in mind), the staff also work on new four villains with different design and personality. After some discussion and testing, the team eventually come up with a sentient prism star (Tsar Starette), a fish-man-like alien (Dr. Stelight), a magician Bloo (Miss Silverenne) and a massive moth lady (Madame Mothana) alongside her weaker form (Floofillar).
Samtendo states that had Waluigi didn't betrayed Wario, chances that he will be one of the Super Henchmen as well, although the least successful in term of how Waluigi would be able to slow down Mario and allies. However, Waluigi would eventually become forgiven by Wario (albeit after Waluigi managed to put up effort and genuinely helped Wario by stopping the ship from crushing) to keep the status quo of their usual relationship.
Other Main Case Characters[]
For the reoccurring characters, such as Luigi and Peach, the team decided that most of them will also be captured by Wario as Partner Cards, but the rest like Peach and Toadsworth are safe and sound (though Toadsworth will get caught in a Partner Card by an accident). This eventually extends to the main villain himself, Bowser, alongside some of his more notable troopers and his own son, to be captured as well, which can also serves as a reminder that Wario is not a push-over in this game.
Gameplay[]
As mentioned before, the game didn't originally planned to have Partner Cards, and is supposed to center around clothing and costume-based abilities, but the fact that it would means four for Mario and four for the new Partners means that it will cause creative strain. As a result, the costume-based abilities are removed, but some of the Moves are moved into Learn Moves.
There were originally have playable interludes for more characters, such as Luigi and Peach. However, the developers decided to put more focus on the war between Mario and his friends versus the W.I.L.D., and as a result only Wario have his own interludes, to give the player an idea what Wario's next plan to stop Mario could potentially during each interlude.
Collectibles[]
According to some employees, there were supposed to be another type collectible to collect, which are either the Power Moons, Blue Coins or even imprisoned people like Toads. According to those developers, any of these collectible would be used to unlock the next world. However, Samtendo declined this idea and said that collecting Partner Cards can prove grueling enough, thus it would also be used to unlock upcoming worlds instead.
Speaking of Partner Cards, the original plan is that every Partner Cards will be simply collected, even the more important characters. That said, other methods to find the Partner Cards are added in order to prevent the Partner Card hunting from getting monotone, from some Partners being brainwashed and serving some higher ranks, to even a very few stocked in a few shops by accident.
Secondary Battles[]
Previous plans for the "secondary battles" were written before, such as Partners forming themselves to make vehicular shapes, such as a tank, a battleship and even a large plane. That said, the battle would be too similar of the Giant Battles from the Mario & Luigi series, but slower, and the developers wanted to try a different one.
Another idea was, instead of vehicles, the player will have more Party Members to deal with bigger threats, such as Madame Mothana. However, the developers eventually agreed to have the bigger threats handled in different ways, such as activating a trap to weaken one of them.
It eventually boils down into Army Battle, which have some similarity of Minion's Quest but retained the turned-based RPG feels of Paper Mario. There were supposed to have 50 per team, but it ended up reduced to around 20 in order to prevent it from getting too pressuring and complicated.
Partner Cards[]
Partner Cards were supposed to be used on the field as well in addition of extra interactivity such as dialogues, but the developers eventually realizes that it would result an overabundance of field-available Partners, so the field usage will be more focused for the new, Card-less Partners.
Giving them extra dialogues in the non-battle Cutscenes will also put severe strain does to translation of multiple languages, thus the extra dialogues are either moved to the battle cutscenes or outright removed. The Tattling for Partner Cards, on the other hand, remain intact, although most dialogues from past games are reused for old enemies.
As stated above, the Partner Cards are done in order to have as many of Mario's old Partners as possible into one game without shoehorning them all in the same plot. This is also to allows new Partners to shine more, and only a couple of Partner-in-Cards have a slightly more importance to the final game's plot than others.
Wario and Miss Silverenne being responsible for the cards, and then Wario using them to capture as many of Mario's old Partners (and even some of his long-time allies), was the fact that the developers feels that they should be introduced in a gut punch to the players who played the prior Paper Mario games, and as a shock factor for the players that are new to the franchise, but also to be used against Wario himself (demonstrated with Kamenia using her magic to free Mario's Partners).
Shine Sprites were planned to return, with possibly the same function it had back in The Thousand-Year Door, but it will prove to be a nightmare in practice does to +100 Partners, thus an alternate is to simply have them upgraded with the Blue Spheres. Later entries that included the Partner Cards also have a get-around such as upgrading them with just Coins.