Jr. Troopa is a resident of Smash City, a student of the dark campus of Cocoon Academy, and a minor antagonist in Super Smash Bros. Crossover starting with Season 20. Jr. Troopa is first seen picking on Kracko for staying at Cocoon Academy on a weekend before "Sasuke Uchiha" (really Coredegon in disguise) breaks up the fight. Jr. Troopa tries to get "Sasuke's" autograph, and learns that "Sasuke" lost his fragment of the Smash Core. Jr. Troopa then reveals that there is a Battle Armor that is so powerful, it was moved away from Cocoon Academy and can only be won when someone beats a Pro Duelist on their first try. Jr. Troopa and Kracko then join "Sasuke's" cause, albeit unwillingly.
Jr. Troopa's main appearance is based off his base form in Paper Mario.
Like in Paper Mario, Jr. Troopa is a bully, shown when he picked on Kracko in his debut. Jr. Troopa is also a delinquent, as he had to clean up the hallways of Cocoon Academy. However, he has deep respect for Sasuke Uchiha.