A Transformation is a change in physical form which usually comes with a significant boost in power.
A human or animal can undergo a normally irreversible transformation into a Mysterious Being by different means:
- A human or animal can transform into an Unusual Type monster through their feelings, e.g. because of their obsession for certain things, of through hatred. For example, Crablante transformed after consuming too much crab.
- A human can also become a "half-monster" in this way. For example: Garou.
- A human or animal can become a monster from injecting or eating the uncooked cells of a monster. For example: Choze after eating a Monster Cell.
- Through science a human can transform into a monster. For example: Marugori through Biceps Brachii King.
Several Mysterious Beings possess the ability to transform; morphing into an alternate, more powerful form.
Some Mysterious Beings have high willpower and possess the ability to transform back and forth between monster and human, although in some cases this requires a great deal of training, as seen with the ninjitsu training Gale Wind and Hellfire Flame went through. Only Surprise-Attack Plum, Gale Wind, Hellfire Flame and Haragiri are known to have this ability.
Puri-Puri Prisoner refers to his "Angel Style" as a transformation, as he significantly increases his muscle mass, a side effect of which his clothes get torn off.
Several of the House of Evolution's mutants possess unique transformation abilities. Mosquito Girl is able to undergo a Metamorphosis (変身, Henshin) upon obtaining enough blood. Carnage Kabuto can undergo a transformation into Carnage Mode (阿修羅モード, Ashura Mōdo).
The alien Boros is able to utilize Power Release (パワー解放, Pawā kaihō) upon the removal of his armor to transform, and after releasing this power he can transform once more using Meteoric Burst (メテオリックバースト, Meteorikku Bāsuto).
Under the right circumstances, Centipede monsters (such as Senior Centipede) possess the ability to transform via Molting (脱皮, Dappi); increasing their size, granting additional armor and giving them an extra face.
Through his shape-changing box, the cybernetic hero Drive Knight is able to undergo a Tactical Transformation (戦術変形, Senjutsu Henkei) into a variety of different forms:
- Knight (桂馬, Keima)
- Silver (銀, Gin)
- Chariot (香車, Kyōsha)
- Flying Chariot (飛車, Hisha)
- Bishop (角, Kaku)
- Gold (金, Kin)
The Monster King Orochi has a great amount of control over his body. He is normally in a humanoid form, but is also able to transform his body into his "released form" composed of snake-like dragons, teeth, and claws. He can also condense himself into a slimmer humanoid form with dragons for hair.
With each Resurrection, Phoenix Man gained the ability to take on new forms, with his first resurrection he took on a permanent state which raised his disaster level from Demon to Dragon and allowed him to utilize:
- Phoenix Fire Falcon Mode (フェニックスファイヤーファルコンモード, Fenikkusufaiyāfarukonmōdo)
- Phoenix Prominence Hawk Mode (フェニックスプロミネンスホークモード, Fenikkusupurominensuhōkumōdo).
Upon his second Resurrection Phoenix Man took on a new form called Phoenix Brilliant Eagle Mode (フェニックス金剛(ブリリアント)イーグルモード, Fenikkusu Buririanto Īguru Mōdo)