A tree design could be cool. But an actual tree this time, and not a Fighting Pokemon disguised as a Rock-type Pokemon that likes to parade around as a Grass-type Pokemon but actually hates water. Yeah.
But a real tree could be cool. Or maybe even like a dryad sort of idea. That might end up as a Ralts/Gothita sort of thing, then, which I've kinda gotten tired of. But maybe a sapling-girl sort of thing that becomes a woman that's made of vines or bark or something?