[@Zeroth] Reincarnation was randomized, so no particular prerequisite. 

For now, just vague glimpses and ideas of their past life, but that'll only be temporary.

I'll be basing everything I know from recall, so evolutions, monsters, and story will mostly be from me. Well, unless I remember certain parts of the source materials right.

Only thing you need to be familiar with would be any isekai story; probably ones with overpowered protagonists, since it'll help you get the general vibe we'll be going with.

As for knowing how certain skills or evolutions work, not really or not so much, since I'll be using a mishmash of stuff plus my own ideas.