In Super Mario World, the Rexes are one of the first enemies encountered. It takes two stomps to their head to defeat them; the first one will reduce their height and increase their running speed.
Mario & Luigi: Superstar Saga
In Mario & Luigi: Superstar Saga, they are found on Hoohoo Mountain with Beanies and Dry Bones. A jump decreases their height, and a second decreases it even more, making their charge attack easier to dodge. At full height, however, they automatically hit.
In Super Princess Peach, they appear in Fury Volcano. Rexes can be flipped over if Peach stomps on their head twice. Swinging Perry at one takes it outright, regardless of where on their body the creatures get hit. They have their own vibe variant called a Sad Rex.
Go, Goomba, Go! • This Beans War • For the Love of Hammers • Winged Traitors • The Hoohoo Melee Brigade • The Great Hammer Barrage • Don't Fear Flying Foes • Goombas vs. Goombas • The Amnesiac Koopa King • Goombas Galore
Turnip Tantrum • Minions vs. Minions • Hunger Pains • A War of Shy Guys and Flybys • Battle Tail • Beanbean Crossfire • The Rival Trio • Larry's Fortress • Captain Shy Guy Trial • Professor E. Gadd's Research • Oh, Hi, Shy Guy! • Shell Brigade, Move Out!
The Sweet Smell of Soda • Deep Trouble • Forest Masquerade • Reclaim the Red Goblet! • Gold Beanie Appears • Invisible Leaderership • Ice Guys Finish Last • The Tough-As-Nails Squad • Forest Fight • Popple's Partner • Captain Goomba Trial (Gold) • Shy Guy Goes Overboard • King of the Boos
A Dry Bone to Pick • The Trouble with Toads • Flying Beans in the Desert • Find the Invincibility Mushroom! • Gold Beanie Spotted! • Silly Ol' Goomp • Ice Bros. Feel the Heat • The Lonely Koopa Troopa • Toad Rescue • Captain Koopa Troopa Trial • Popple's Partner, Part 2 • A Goomba Tail • A Muster of Masks
Goombas Unite • Gather the Cruiser Parts! • Power Play • Spear Party on Ice • Monochrome Explosion • Gold Beanie Fights Back! • Return of the Koopa Cruiser • The Trio's Last Stand • Captain Boo Trial (Gold) • Boo Party! • Shy Guy Barrage
Fireball and Boomerang Crossfire • Chain Chomp and Spike Stomp • A Tale of Tails • Double Trouble Koopaling Caper • Pokey Panic • Rumble in the Castle! • Gold Beanie's Final Stand • Goomba's Worth • Showdown Time!! • Believe in Bowser • Captain Boo Trial • The Mightiest Minions • The Beastly Bean Battalion
• ⋆-Enemy, boss, or stat exclusive to the main game. • ⋆⋆-Enemy, boss, or stat exclusive to Minion Quest: The Search for Bowser. • ⋆⋆⋆-Enemy variants differ in Mario & Luigi: Superstar Saga + Bowser's Minions.