Salvo the Slime

Salvo the Slime is the boss of World 1 in the game Super Mario World 2: Yoshi's Island. Salvo is a Slime Drop that was enlarged into a Slime by Kamek. Salvo jumps at the player, trying to push them into a lava pit below his arena, though unlike most enemies, the player is not hurt by Salvo's touch. Instead, the Yoshi is hurt by the Slime Drops that Salvo summons. Because Salvo was a Slime Drop prior to his transformation, Slime Drops break off of Salvo when he is hit by an egg. The more Salvo is hit, the smaller he gets, until he disappears altogether. He also is seen in the end of Door 2 in 6-8: King Bowser's Castle. Before the door with him, there's an Egg-Plant that produces eggs.

Salvo the Slime appears in Mario Party 4 under his Japanese name, Big Slime. During the minigame Slime Time, four of him appear in darker yellow, pink, purple, and green variations.

Going only by his first name, Salvo makes an appearance as the boss of the second floor of the Duel Tower in Mario Party Advance. This game shows that he is capable of speech. Salvo challenges the player to a game of Volleybomb and rewards the player with a mini-game upon defeat.

He also makes a brief cameo alongside other Super Mario World 2: Yoshi's Island bosses in the opening to Yoshi's Island DS.

Trivia

 * Although Salvo is indeed a name (actually a surname), its use in this character's name is likely a pun on "saliva," referencing his slimy texture. It may also refer to how it discharges multiple Slime Drops (i.e. a "salvo") when hit by an egg.