When Super Dragon is used, Yoshi will gain wings and is able to breathe and spit out fire. Yoshi is able to move around freely around a stage and is invincible while in this form. Yoshi's fire spit attack deals moderate damage with moderate knockback while his fire breathing can rack up in damage (but Yoshi must be close to an opponent). This transformation lasts about 10 seconds.
The Super Dragon may be based on Yoshi's various of abilities from Super Mario World. If Yoshi eats a Koopa Troopa with a blue shell in that game, he will gain wings and if he eats one with a red shell, he will be able to breathe fire.