All this Evee talk is making my head spin.
I think my main problem is that any pokes we get will be WYSIWYG with regards to evolution rank and move set. With so many players, there will
always be one stray button press to interrupt an evolution or discard a new move. Once all four move slots are occupied via normal level up mechanics, that's that.
Additionally, the only hope to consciously affect the move set of a Pokémon is a TM or HM - and that's a whole new can of worms in itself since we're just as likely to overwrite important moves. Just ask Abby (Mr. Bide&Cut).
So, methinks we need to look at possible party members not in terms of potential, but in terms of viability "out of the box".