there is a move named fling,wich throws the held item to the target.the damage and the effect differs depending on the item,if the Pokemon holds a wing the base power of the attack is 20.unfortunately there are much more items wich give even better base power to the move and even items with effects such as burn.
also if the opponent uses the move trick against you(tric is a move wich allows you to switch your item with the target)they will stuck with the preety wing wich does nothing and cannot be used against you.
also there are Pokemon with ability pick up,so if they steal your item,it will not be a bad loss.( I am not sure if they steal your items,I could be wrong)
