Bahamutt

Bahamutt is a colossal dragon encountered by Mario and his allies while exploring Bowser's Keep in Super Mario RPG: Legend of the Seven Stars. Both Chester and Magikoopa can summon him to help them in battle, as he is indeed a powerful foe. Bahamutt has a lot of HP and above average stats. Besides regular biting attacks, the dragon can resort to the special moves Iron Maiden, which triggers a Fear status ailment, and Drain.

Despite being very strong, Bahamutt doesn't seem very confident in his own abilities, as revealed by his Psychopath thought.

Trivia

 * Bahamut (with one "t") is a powerful dragon from the Final Fantasy series and Bahamutt's namesake. The two creatures, however, hardly look alike.
 * It is possible that the Final Fantasy Bahamut is named after "Bahamūt", an alternate spelling of "behemoth", a mysterious creature (thought by several to be a dinosaur) mentioned in the Bible's Book of Job. If this possibility is true, Bahamutt is indirectly named after the behemoth. It's also, however, possible that Final Fantasy's Bahamut is named after the Bahamut character in Arabian mythology (an omnipotent being who rides on a whale's back), which would make this Bahamutt's indirect namesake.
 * There is an unused sub-species of Bahamutt in Super Mario RPG: Legend of the Seven Stars who resembles Boshi, with purplish coloration and pointed sunglasses. It has no psychopath and can use the move Flame.
 * Bahamutt may be based on Yoshis. Its Japanese name is similar to Yoshi's name and that the creature loosely resembles Yoshis.