After Goldenrod city, the guard guy thats at the gate to the next route gave me his spearow to give to his friend at route 31. I can imagine other characters doing this later on in the game. But what happens if after I finish his request a friend gives me that spearow in a trade before he does that mini quest? Would I be able to do the quest again or will it mess up my game somehow or will nothing happen? Unless it's impossible to trade it. I like to collect the NPC's pokemon that you normally get from a trade in the game.