Rayquaza

Rayquaza (レックウザ, Rekkūza) is a Legendary Pokémon who first appeared in Pokémon Ruby, Sapphire, and, most prominently, Emerald, where it was featured as the cover Pokémon.

It is the first confirmed Pokémon character in adventure mode of Super Smash Bros. Brawl.

Rayquaza in the Super Smash Brothers series
Rayquaza first appears in the jungle after Diddy Kong goes to investigate a crashed Arwing. It comes out of the water and attacks the Arwing with Dragon Pulse, then kidnaps Diddy. As it goes back in the water, Fox McCloud comes out and attacks Rayquaza, causing it to lose its grip on Diddy Kong. The Pokémon attacks Fox with energy, but Fox reflects the attack back at Rayquaza, sending it tumbling back into the water.