Like most enemies, Skellirexes have a repeated pattern of walking left then right. If Donkey Kong and Diddy Kong come in contact with a Skellirex, it bites them and they lose a heart. The Kongs can safely attack Skellirexes with any attack. By doing so, the Skellirex loses its body, and its head detaches and forms into a Skullyrex. The Kongs can instantly defeat a Skellirex by directly attacking its head, and they can also instantly defeat the Mine Cart-riding Skellirexes by jumping on them.
A Skellirex appears in concept artwork, where it more closely resembles a Tyrannosaurus and is missing its crest.