The PP up are rare only one time items, once you find and use them all there will be no more. You will need a Gameshark or Action Replay to obtain more, here are the current locations.
Cerulean City/Five Island/Water path/Cerulean Cave
There are more that can be found hidden, but you will need a Itemfinder. You can also use a Pokemon with the ability treat Pick up like a Pokemon Meowth would have, and you could pick it up when walking or battling.
Ok topic, solved now I will close it closed.
Yawn - what is there to say?