I love the sprites
I know the battle (I don't draw hentai but I draw a lot of characters). It'll take a year or two for you probably to get your speed up. It doesn't really come with practice from my experience but with artistic maturity (time). Don't be afraid to do lower resolution images, like 8-bit style if it helps. That can be really hot as well if animated. As a side-note, I love the side scroller aspect of the game in the tavern as well in between duels. It creates a more welcoming feeling than previous games of yours which is very nice. The gameplay of course can be improved upon a lot but that's not the main importance right now.