Monster X is a bipedal creature with an exoskeleton-like armored skin. He possesses two small half-skulls on his shoulders and a long black forked tail. Monster X has red eyes, a skeletal face, and long spikes on the top of his head.
Keizer Ghidorah incorporates elements of both King Ghidorah and Desghidorah in his appearance. Like Desghidorah, Keizer Ghidorah is quadrupedal, and like King Ghidorah he has golden skin. Keizer Ghidorah has much smaller wings than the other Ghidorahs, and lacks defined scales on his skin, instead having smooth gold skin with bluish streaks and spikes erupting from multiple spots on his body. Keizer Ghidorah's middle neck is much longer than the other two, and each of his heads has a different arrangement of horns and spikes. Keizer Ghidorah also possesses two long, whip-like tails.
Monster X's abilities include gravity beams from his three heads' eyes, rapid melee attacks, impressive agility, and transforming into the more powerful Keizer Ghidorah. He is also shown to levitate for a short period of time. Even before transforming, Monster X is still extremely powerful. He is a physical match for the Mane Six and his gravity eye beams possess roughly the same strength as the Elements of Harmony and Rainbow Power beams.
Like King Ghidorah, Keizer Ghidorah is able to fire gravity beams from his mouths. These beams are stronger than the Elements of Harmony and Rainbow Power beams. Keizer Ghidorah can also guide their paths and pick up and throw objects with them. Keizer Ghidorah can drain energy through his bite. Keizer Ghidorah also has the ability to fly.
- He is over three thousand years old.