How about GBA style?
each attack got XX PP
http://pokemon.wikia.com/wiki/PP
PP are refilled after visit in poke center or by use
http://bulbapedia.bulbagarden.net/wiki/Ether
And hmm something like, you can use each attack after per seconds
and like in gba, wild pokemon have to! use some attack per this X sec. He can use "useless" attack like harden, but ge also can use his strongest attack for example ice beam and totaly miss. like in gba
this X sec valuse should be somelike to simulate turns in gba
i dont tell you what to do, just give random ideas...