Spewart appears to be the Broodals's entertainer. He, while strong, may not be one of the smartest. His Dark Side Kingdom Brochure bio shows him to have an artistic side, even though his poison puddles have no pattern. It also shows his nature as the least subtle of the Broodals.
Spewart appears as a separate boss three times in Super Mario Odyssey.
In battle, Spewart can spit poison. At the beginning of each round, Spewart will surround himself with his poison, then start going after Mario to spit poison at him. Mario must use Cappy to knock Spewart's hat off, then jump on him for damage. After that, Spewart will fly around in a saucer fashion and cover the field with his poison. After being jumped on three times, Spewart will fall in defeat.
Spewart re-appears in the Luncheon Kingdom, where the Broodals are after a pot of Stupendous Stew. His move set and battle tactics remain similar to his first encounter, with the only difference reflected in a larger battle arena.
Spewart appears with the rest of the Broodals in Bowser's Kingdom, as they pilot the RoboBrood.
Spewart appears on the Dark Side, and states his plan is to take the Odyssey from Mario. His boss fight is similar to the first encounter in the Wooded Kingdom. Spewart appears after Hariet is defeated, and Rango comes next.
Dark Side brochure
Spewart, the Entertainer
Is the vulgarity all an act?
Spinning around while spitting poison in a wide area, Spewart is the least subtle of the Broodals. But he also has an unexpectedly artistic side, as his poisonous ground-paintings show.
- Spewart apparently earned his name from a pun on "Stewart" and "to spew".
- Unlike Topper and Harriet, who either gets stunned or panic when their hats come off, Spewart will continue chasing Mario even if Mario knocks off Spewart's hat.
- When Mario jumps on Spewart, every bit of poison on the field at the time will clear out.
- Throwing Cappy over Spewart's poison can clear out some of the poison.
- Along with Rango, you don't have to fight Spewart to beat the game (other then in the Robobrood). It is possible to skip his Luncheon Kingdom battle by using a Life-Up Heart to get to Salt Pile Island, then taking more damage to get to the nearby doorway, then using the small wooded spikes. From there, you can explore and collect around 18 moons, but many enemies have not yet spawned (such as Hammer Bros, and some Lava Bubbles).