Mechakoopa
Mecha Koopas are one of Bowser's many minions. They are mechanical versions of Koopa Troopas. They get paralyzed for a short time when stepped on, so Mario can kick them around and pick them up and throw them. When they get thrown however, they don't get very far like regular Koopa shells do. Also, they are technically invincible unless they are kicked or thrown at an enemy because they always reanimate after a few short moments, much like Dry Bones.
They make a short appearance in Super Mario World, where they only appear in the last World. The final boss of the game, Bowser, throws them off of his Koopa Clown Car, the hovering clown machine he occasionally can be seen riding in. Mario and Luigi must throw them up so they hit Bowser's head. They are like a cross between a Koopa and a wind-up toy. They have a wind-up key on their back and their appearances are quite comical. They walk in a rhythmical way and they must wind themselves up again from time to time.
Bowser later uses a giant, green one as a weapon in his Super Mario RPG: Legend of the Seven Stars attack Bowser Crush.
In Mario Party 5, the player fights a group of them in the first part of the final battle. They walk around, occasionally flashing red, then unleashing fiery breath. Jumping on them once will cause them to explode. Jumping on a flashing Mecha Koopa, however will hurt the player.
In Mario Party 7 Mecha Koopas appear in the 1-player Bowser mini-game, Tunnel of Lava!, where one Mecha Koopa eats the key to freedom from Bowser's mini-game area and retreats into a hole, only to come back a second later with many other Mecha Koopas. The Mecha Koopas would then circle the character, who would have to stomp on the correct Mecha Koopa's head while they circle him/her before Bowser stomps on the character 30 seconds later. The Mecha Koopas have an attack pattern similar to that found in Mario Party 5, except all the Mecha Koopas will breathe fire simultaneously. Mecha Koopas have also made small cameo appearances in Mario Power Tennis and Mario Party Advance.
Mecha Koopas make a short appearance in Mario & Luigi: Superstar Saga in Woohoo Honiversity and Bowser's Castle, where they are used as conductors to complete circuits of electricity. Organic versions of Mecha Koopas appeared in Mario Kart Super Circuit.
