By the way, could we invoke some lore of my invention? That in wild battles, you can use any items without restriction. But in trainer battles, you usually define what item level you run with.
FREE MODE or WILD MODE is where everything goes. Do what you can to keep your pokémon up and running!
NO CURE would be the simplest "trainer battle" level, where stuff like poison heal, awakening etc isn't allowed until the battle is over. But one potion per pokémon is okay to use! This is usually how it's like when you meet a random trainer on the road; if nobody states any rules before a battle, you assume that NO CURE is what goes, and you're allowed to heal each pokémon at one critical point if you have a potion and can reach your pokémon without getting hurt yourself (!). Most often you can use as many pokémon as you have on you, to try and beat all your opponent's pokémon, but you can also define how many pokémon you want to use.
NO POTIONS is the next level, usually deployed in Gym Leader battles. You can't use curing items nor potions here. You'll have to rely on moves, strategy and switching in and out. Unless switching in and out is forbidden too, but that's special rules and not often deployed. In gym leader battles, the number of pokémon you can use is usually defined.
RARE items are always allowed though... such as the REVIVE you can get in event 1, chapter 2, and also some future items. But in general, pretend stuff like X ATTACK, IRON, DIRE HIT, ETHER and such is RARE and you can't just buy it.
... would that work? :3