Talent Arts: All characters can now upgrade their Talent Art, not just Seven. Doing this requires AP and Power Tokens. This does not apply to the Monado Arts.
Power Tokens: Affinity Coins have been replaced with Power Tokens, still being acquired from Unique Monsters. In addition to being used for Skill Links, they can now also be used to upgrading Talent Arts and unlocking Advanced Arts.
Spikes: The power of Spikes has been massively decreased. Topple Spikes have been removed.
Break/Topple/Daze: A number of new Arts have been added to numerous characters like Riki that allow them to inflict Break, Topple, or Daze.
AI: Major improvement to the AI for characters. Shulk will check if characters can inflict damage upon Mechon before using Monado Enchant, Melia will apply better use of Elementals, and Sharla will use Cool Off more often, in addition to other improvements.