What does the Regen role do?

Energy is the blue orbs above your health bar, and a Regen Aniimo keeps them coming back. Faster energy recovery means skills and attacks come off cooldown sooner, and the effect is on the team's pool, not just the Aniimo doing the work.

Regen is one of five roles, alongside DPS, Heal, Support and Break. Every Aniimo has one fixed role that cannot be changed, so you get a Regen by catching one. You cannot respec into it. Do not mix it up with Heal: a healer restores HP to your squad, while a Regen restores energy. A team that is all damage dealers runs dry, and the game rewards mixing distinct roles, which is where a Regen earns its slot.

Regen Aniimo to look for

Besauce works as an energy battery whose restoration is not tied to an element, so it fits any team regardless of what your damage dealer is.

Somniwing's ultimate recovers 50 EP. Use it to refill energy mid-rotation when your other skills are waiting on it.

Which stat a Regen scales with

Not every utility Aniimo scales the same way. Some heal off HP, some scale with Attack, and some scale their regen effects with a Regen stat. Check which one an Aniimo's kit reads before you put resources into it, because levelling the wrong stat does nothing for its energy output.

Not settled: The role set is not named the same way everywhere in the game: it also appears as DPS, heal, buff, break and debuff, with no separate Regen role in that list.