I understand that certain creatures only evolve when you trade them to another game cart with a certain item attached to them (When you let them 'hold' a special item).
For me, this presents a problem since I believe you can only get 'one' King's Rock and there are actually 'two' creatures (Poliwhirl & Slowbro) that need it to evolve (Into Politoad & Slowking). The same goes for the other special holding-item-trade items.
My question is: Does the item remain useable after the creatures evolution (i.e. Can it be taken back from the creature once it gets to the other game cart) or does the creature ABSORB the item to evolve?
I don't evolve one only to lose the chance to evolve the other ... Someone please help by answering me.