Took me a bit to understand how to do the charge shot but when I did the game became pretty boring quick.

Just add that score system and AI you were talking about and this should be a really fun time waster. Good luck with it.

Good sound effects and sprites. Not sure about the grid system though.

The character sprite art is really cute. Having the character snap back to the center was a little disorienting for me. I was able to receive the beach ball but had a lot of trouble with the volley ball so I was probably misunderstanding the gameplay/controls. Seemed like after I set the ball I couldn't hit it again - though maybe I'm supposed to charge and hit it back with that?

Looking forward to seeing this developed further.