ZZAZZ glitch
From Bulbapedia, the community-driven Pokémon encyclopedia.
A glitch that is caused when the Mew Trick is done with the decimal number of 251, 252, 254, 255, making you encounter a glitch trainer that forces this glitch to occur. It has also been known to cause the opponent's Pokémon (usually a Charizard 'M) to become "invinsible. This is also a side-effect of using Super Glitch.