Masher is a real heavyweight.
Meta KnightKirby: Right Back at Ya!
You said it!
Tiffto Meta Knight, Kirby: Right Back at Ya!

Masher is "the strongest demon beast" and also one of the few that was not directly ordered by King Dedede in the episode "Monster Management". Instead, Knuckle Joe (as Monster Manager for Nightmare Enterprises) ordered it after ordering several mini-monsters. Kirby, now weak after fighting the mini-monsters, is forced into a fight with this hulking beast. However, Knuckle Joe double-crosses Masher, and together, he and Fighter Kirby overpower it until they finish it off with a Rising Break, destroying it. The monster later reappeared in the episode Masher 2.0 as the similarly-named Masher 2.0.

Masher not only has massive physical strength and can swing around its huge flail with ease, but despite its size, it can also fly using the jets hidden at the bottom of its shoes, spinning rapidly to strike the opponent.

It was also an enemy in Kirby's Dream Land 2. Here, Masher is one of the clan with Blade and Butch, and still attacks with its mace. In this perspective, Masher could be seen as an early design of Mace Knight.

Masher is also one of the only monsters that manages to injure Meta Knight (The other being Wolfwrath). As Meta knight leaps to attack Masher, it swings around its giant flail and clobbers Meta Knight hurling him into the cliff.