When it Mega Evolves, Gyarados becomes bulkier. The fins on its cheeks become longer and gain a yellow tint. Its crest is larger and black, and its barbels also gain considerable length. A large spike extends downward underneath its chin, and it now has a black underside with a red stripe around the edges. The yellow spots along its body are replaced by raised red scales, which propel Mega Gyarados through the water. Two large yellow fins with blue spines appear on its back. Most of the other fins along its back disappear, replaced by two rows of blue spikes. There are now four yellowish, spiky fins near its tail: two on its back and two on its underside. While its brain has a powerful destructive instinct, it will obey a Trainer it truly trusts. Mega Gyarados is tied with Hoopa Unbound as the tallest Dark-type.