The color switcher seemed unresponsive at times. It's also not really clear how battles are meant to be triggered. The description says they're supposed to be available when you have 10+ items, but I've been able to trigger battles with less items, and also been unable to trigger battles with more ... actually, that has me curious if you have a greater-than/less-than in the code that needed to be reversed.
It's admittedly annoying having no influence over the battle going on. Ie, berries are pointless to get and just waste a turn if you have none, so they probably shouldn't appear when you have no berries. on that note, using berries at full health is wasteful, so perhaps make it so no berries are used if the player is at full health.