Salvo the Slime

Salvo the Slime is the boss of World 1 in Super Mario World 2: Yoshi's Island and its remake. Salvo is a Lemon Drop that was enlarged 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, Yoshi is hurt by the Lemon Drops that Salvo summons. Because Salvo was a Slime Drop prior to his transformation, Lemon 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.

An alternate variant of him appears later as a non-boss enemy in the game, known in English simply as Slime. It can disguise itself as a block, and is defeated the same way. Slimes appear again in Yoshi's New Island.

Four different Salvo the Slimes appear in Mario Party 4 under his Japanese name, Big Slime. During the minigame Slime Time, the four versions of him appear, in yellow, pink, purple, and green.

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 the minigame 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.

Super Mario World 2: Yoshi's Island

 * Official Nintendo Player's Guide: Yoshi's last stop in World 1 is a castle, but the greeting he gets there isn't exactly chivalrous! Before checking out, Yoshi will have to cope with this enormously icky enemy. The slow-moving Salvo skedaddles faster and faster the more he's hit with dino eggs, but he also throws off lots of Lemon Drops. Besides tasting great, these make excellent eggs!
 * Shogakukan guide: プルプルしていて、ぶつかるとバネのようにはじかれる. タマゴを当てると小さなスライムに分裂する. (It pulls and springs back when bumped into. When you hit it with an egg, it splits into smaller Slime Drops.)

Mario Party Advance

 * "Don't underestimate me because I'm beefy! I've got skills you've never even heard of!"
 * "If you beat me, you can have the Duel game. Lose, and you get nothing!"
 * "Let's begin!"
 * "My skills were no match for your own! Time for you to head to the third floor."
 * "You did it! And that means you can go on to level 3! There, the fiercest duelist awaits you!"

Trivia

 * Although Salvo is indeed a name (actually a surname), its use in this character's name is a pun on "," referencing his slimy texture. It may also refer to how he discharges multiple Slime Drops (i.e. a "") when hit by an egg.
 * In his artwork for Super Mario World 2: Yoshi's Island, Salvo is beige, while in-game, he is green.