[Scripting Question] How do I assign an item to identify a Pokémon?

[MessiDuvidoso]

How do I assign an item to identify a Pokémon?
I want to make an item that gives a Pikachu a new shape that will be an Addon system in my game. BUT I need this item to identify a Pikachu, and not give shape to others, how do I do this?

 

[GT-Baka]

When you say "give shape" do you mean a new form like how the Gracidea Flower changes Shamin to Sky form, or do you mean like give the Pokemon a new Pokedex category body shape?