Muscle Mass Enhancement is a psychic abilities that allows the user to get alot bigger with the muscles and more bigger than ever from their own body.
In the Super Baxter Series
Various users have used this ability to gain alot more scarier and alot more stronger than ever. Typically most of these come from the Ground Elements.
In the Real Life Series
Various Species from the Real Life series have used this technique. Most commonly it's Sonikku who uses the most of this move from out all of the other characters.