This Would Be My First Choice:

Just Look At How Awesome He Looks, Specially With That Aura Sphere About To Bust Something Up.

2nd:

Just Cause He Is Amazing and REALLY Hard To Kill, For Strategic Reasons...
And He Just Looks Awesome And Strong Too.

3rd:

Atrocious...Thats Actually What It Is In the Pokédex: Gyarados, The Atrocious Pokémon
No Words Need To Describe Its Notoriety And Its Awesomeness.

4th:

Just Look How Beautiful That Thing Is...DAYUMN!!!