Knuckles

Knuckles appeared in Tiny PP & Knuckles and Big Chungus 2 & Knuckles. His best friend is Tiny PP. He also fights alongside Big Chungus in Big Chungus 12: Sans Undertale vs Big Chungus.

About
Knuckles the Echidna (ナックルズ・ザ・エキドゥナ Nakkuruzu za Ekiduna?) is a fictional character from the Sonic the Hedgehogseries. He is an anthropomorphic echidna and the current guardian of the Master Emerald, a powerful ancient relic which is his solemn duty to protect from anyone seeking to abuse it. He is also the sole remaining descendant of the Knuckles Clan and last of the echidnas on earth. His dominant traits are his super strength, and the two spike-like knuckles on each of his hands, from which his name is derived from, which he can use to dig with and climb walls. He can also trap the wind under his dreadlocks to glide through the air.

A loner by nature, Knuckles is independent, headstrong and serious, yet gullible and short-tempered to a fault. He is entirely devoted to his duty, spending most of his time on Angel Island protecting the Master Emerald, and rarely cares for anything that is of no importance. When his friends and others are in need of his help, however, Knuckles can always be relied on being willing to leave his post and prove himself a faithful and good-hearted hero. He is also one of Sonic's oldest friends and rivals.