That would highly appreciated. So far I have only finalized Pokémon, no spells or lands, and for Pokémon it's easy to find art for.
Well, you're aiming for quite a high power level, so I felt insecure about commenting those, as I figured, it might just be what you want here. For example, a 1-mana 3/2 (Bulbasaur) seems odd to me. But if you want those to be really trog, there is nothing wrong with that. Also, Venusaur being a vanilla as well seems wasted. I know you wanted to keep it so each starter would be another, but maybe that's not worth restricting yourself by? After all, there are so many Pokémons in the cube, those battle won't come up all that often.
For inspiration, my Bulbasaurs are all 2-mana 2/2s with reach (not sure about the english attack names, but you kno, with it's vines it can probably block pidgeots?). One of them gains you 1 life each turn, one of them has basically unnamed outlast for
(that growth move),and the third one has
,
: Target Pokémon is now poisoned (I have marker card for the status changes, poison gives you a-1/-1 counter every upkeep).