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.
 * Final Fantasy's Bahamut is most likely named after the Bahamut of Arabian mythology, an omnipotent being who rides on a whale's back. By extension, the Arabian Bahamut is also Bahamutt's namesake.
 * A version of Final Fantasy's Bahamut was also supposed to appear in Mario Sports Mix, but was taken out.
 * 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. If a Yoshi Cookie is used on a Bahamutt, Yoshi will swallow it and produce a Yoshi Candy item (which is normally earned if Yoshi fails to swallow an enemy).
 * In addition, it shares the same Japanese name as Dorrie, which made its debut shortly afterwards. It could be that these dragons are closely related, as they also have a close physical resemblance disregarding their obvious limb and eye design differences.