For example, Cyber is immune to Electric, and weakens said type. While Steel isn't weak against Cyber, it doesn't weaken Cyber either. Its other big strength is against Psychic.
Its biggest weakness is the very common Water type, and its other weaknesses include Fire and Poison. Finally, Grass is able to resist Cyber attacks.
Fanon Cyber Pokémon are based on anything that is electronic data, digital programs or futuristic machinery. Animals of this type are no less than portmanteaus. A bunch of extraterrestrial Pokémon may make use of this type as well, according to the thought that certain alien lifeforms are highly intellectual. As it is thought that the future would bring many complicated and weird-looking apparatuses, some of the Cyber-type Pokémon are from the very far future.
In Mr. Yokai's Pokémon game, this type is related to advanced technology that Steel couldn't simply fit into (this does not go for all Pokémon), but also apps to expand the possibilities. Not just that, it is also related to computer-related things, such as keyboards and mouses. This does not include everything related to a computer, nor all the artificial Pokémon.