Fizzlit

Fizzlits are small blob-like enemies that first appear in Super Mario Galaxy 2. Their body is purple with eyes that have yellow pupils and black sclera, as well as a wavy mouth. In Super Mario Galaxy 2 their bottom is tooth-shaped while in Super Mario 3D World their bottom resembles a suction cup. They turn into a yellow electric puddle that is either a square or a circle when attacking. Their name is likely a play on the word "fizzle", possibly combining it with "lit" in reference to how it lights up yellow when electrifying.

Super Mario Galaxy 2
Fizzlits first appear in Super Mario Galaxy 2, where they attack by hopping from one place to another and spreading into a round electric puddle with their eyes poking out, which will shock and damage the player upon contact. Fizzlits are only vulnerable when they are in their non-electric state, during which the player can use any form of attack to defeat them. They can also be defeated by eating them with Yoshi. However, they are still harmful when simply touched from the sides. Fizzlits mostly inhabit industrial levels, such as Bowser Jr.'s Fearsome Fleet and Bowser Jr.'s Boom Bunker, but are also encountered in Cosmic Cove Galaxy.

Super Mario 3D World / Super Mario 3D World + Bowser's Fury
Fizzlits reappear in Super Mario 3D World and its Nintendo Switch port Super Mario 3D World + Bowser's Fury, now being roughly square-shaped with connected eyes. They retain a similar method of attack from before, generating an electric puddle in an attempt to damage the player and becoming vulnerable once the attack stops. However, they no longer jump around and are stuck to the ground permanently. The puddle they melt into is now square, and their entire faces can be seen on top of the puddle, rather than their eyes poking out as they did in their previous appearance. The puddles are now smaller as well. When in their puddle state, they either remain stationary or move in a fixed straight path before reverting to their solid forms. They inhabit various levels with various environments, including Switchboard Falls, Tricky Trapeze Theater, Trick Trap Tower, and Switch Shock Circus. They are also featured in Captain Toad Takes a Spin and Mystery House Brawl.

Trivia

 * In Super Mario 3D World, Fizzlits look in the direction they move when in their puddle form.