Flaming Wario

From the Super Mario Wiki

Probably Wario's most famous transformation in the Wario Land series, Flaming Wario. In Wario Land 2-4, when hit by a Torcher (a torch-holding fox enemy), Wario will comically start racing around with his pants on fire. In this state, he cannot be controlled, except for jumping. Soon, the flames will spread across his entire body, making him essentially a living Fireball. He can now be fully controlled (although slowed down a bit) and can destroy blocks with a fire symbol on them. This can be cured, obviously, by falling into water or just waiting until he burns out. Also, it is known as Hot Wario in Wario Land 2. Ball o' String Wario combines this ability with Snowman Wario. In Wario Land: Shake It!, Wario can once again use this form, however it can only be activated by coming into contact with a small fireball creature.

Official Art for the transformation.

Wario completely covered in flame in Wario Land 2.

Artwork from Wario Land 4.

Fire Creatures
Angry Sun | Blargg | Bomb | Burn Bit | Crusher Blargg | Czar Dragon | Ember | Fiery Bubble | Fire Chomp | Fire Elemental Ghost | Fire Snake | Fireball | Fryguy | Fryguys | Gargantua Blargg | Helio | Hot Foot | Hot Lips | Hothead | Kleever | Lava Bubble | Lava Bud | Lava Drop | Lava Ghost | Lava Piranha | Li'l Sparky | Mini Fryguy | Petit Piranha | Phantom Ember | Podoboo | Pyro Guy | Pyrosphere | Sparky | Sun | Torcher | Trouble Bug
Fire-Related Creatures
Baby Bowser | Birdo | Bowser | Bowser Jr. | Calm Volcano Plant | Dhalsim | Dino-Torch | Dragon Wario | Fire Bro. | Fire God (Mario & Luigi: Superstar Saga) | Fire God (The Super Mario Bros. Super Show!) | Fire Luigi | Fire Mario | Fire Wario | Flaming Wario | Flare | Gao | Iggy Koopa | Jumping Piranha Plant | Kerozene | King Totomesu | Lava Lotus | Ludwig von Koopa | Sumo Bro. | Tryclyde | Venus Fire Trap | Vivian | Volcannon | Volcano Lotus | Zeus Guy (Bandit) | Zeus Guy (Snifit)