Grade belts mark progress in I-Ninja, Argonaut's 2003 cartoon platformer about a small ninja scoring his own combat. The GameCube shipped with the PlayStation 2 and Xbox versions, with a master who grades the fights.
Rage and a sword bigger than the hero are the joke, and the levels are bright obstacle courses between those graded brawls. The ninja is small on purpose, so the enemies look like toys he is determined to outrank.
Argonaut's graded ninja is this cartoon. The cube release is one of the three consoles that got it, not a later handheld demake.