When Mew finds an army helmet Mew turns braver and becomes... Army Mew!
Mew with an army helmet is a lot braver.
In the Virtorld reigon there is an Army Mew whose moves are Mega Punch, Metronome, Fly and Roost.
You can also equip a Mew with an army helmet to turn it into Army Mew.
In Army Mew forme, Mew gains atk and sp. atk but loses def and sp. def and its ability becomes Defiant.