In the Ruby field, a Makuhita will be on the right side of the field and is helpful for getting better Pokeballs. To get it to help you, hit the Chikorita on the left side of the field, then hit the Linoone that pops out where Makuhita is located. Makuhita will turn around, and whenever you press the right flipper, he will punch. If timed correctly, he can punch the ball to hit a Nuzleaf that will eventually make a bridge to get an upgrade on your ball.