Hello! All Pokemon start off completely depowered outside of abilities absolutely necessary for their survival (like charmander's flame tail).
As for abilities that can be regained, it has to be abilities that a pokemon is able to learn through the game, and the Pokemon can only know 4 at a time. This applies to any hidden or passive abilities as well. There are thousands of pokemon moves so we can't possibly give you a weigh in on every power, but basically when you're purchasing the ability consider whether or not it'd be allowed in Kaisou on a normal character (so something like a mind control spell would be out, but something like fire breath would be fine).
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As for abilities that can be regained, it has to be abilities that a pokemon is able to learn through the game, and the Pokemon can only know 4 at a time. This applies to any hidden or passive abilities as well. There are thousands of pokemon moves so we can't possibly give you a weigh in on every power, but basically when you're purchasing the ability consider whether or not it'd be allowed in Kaisou on a normal character (so something like a mind control spell would be out, but something like fire breath would be fine).
Hope this helps!