Poke'Fighter

[Kosheh]

This exists and it's called Type Wild. Although the roster is pretty small, I recall the characters looking pretty Sugimori-artwork accurate but it's a dojin fighter.
http://www.pokesho.com/battle

Pretty neat mechanics; every Pokemon has 3 assists to choose from which work a little like the ones from the Marvel VS. titles (1, not 2)

Beta 4 has a selection of eight playable characters AFAIK. Playables include Blaziken, Lucario, Snorlax, Gardevoir and Breeloom.

I'm not sure where to download beta 4.3 but yeah

Wow! It looks like the traditional 2D fighters. Posted a pic here for those who have trouble navigating in Japanese:

HOTLINKING IS BAAAAD
but yeah if you've played fighters the UI is pretty straightforward. Assists and Supers cost PP, which works like it does in any fighter nowadays except there's more stress on the numerical values and knowing exactly how much PP you need to execute attacks/send out assists.