Donkey Kong Country 2: Diddy's Kong Quest/Land 2
They first appear in Donkey Kong Country 2: Diddy's Kong Quest and make their second appearance in Donkey Kong Land 2 and these carts are first found in the level Target Terror in Donkey Kong Country 2: Diddy's Kong Quest and Donkey Kong Land 2. In this level, Diddy and Dixie Kong had to jump from Skull Cart to Skull Cart in order to complete the level. They also appear in Target Terror on where Diddy and Dixie had to defeat many Klanks and in Haunted Hall (Level only in DKC2) on where Diddy and Dixie had to avoid Kackles by attacking them. Lastly they appear in Krazy Koaster, a level exclusively only appearing in DKL2. on where Diddy and Dixie had race through the level to reach the goal.
Donkey Kong 64
These carts make their third and latest appearance in Donkey Kong 64 on where Donkey Kong had to go to Creepy Castle and avoid the Skull Carts and aren't rideable in this game. Instead, these carts contain TNT Barrels which Donkey Kong had to avoid.