When analyzing this next character, we actually don't need to go further than his name: Token Black.
A comment on tokenism, the creators of South Park added a black student to the show in season four. He's now always seen in group scenes and has an occasional witty or sassy line or two, but rarely has much substantial presence with the exception of episodes that center around racism or plots where his blackness is key (i.e. Cartman being charged with a hate crime, or Stan's realization about the "n word"). He's self-aware of how out of place he is, but still wants to be a part of the group--essentially, resigned desperation turning into an attempt to make the best of an unfortunate situation.
I would argue that Token is a positive representation. While he's the lone black student, we're supposed to be fully aware of this discrepancy, and revel in its ridiculousness. His name makes that clear. The writers weren't adding him to be racist saying: "hey, we make fun of Jews, fat kids, and the poor--let's attack black kids too!" Rather, Token is there to make a point, and subtly make fun of those who do think like the previous statement.
In this clip, Token "magically" discovers that he can play the bass. He's never picked one up before or had a single lesson, but all black people can play bass--that's just obvious! He's only doing this to help the white kids in his class. While it's not as degrading an example as most magic engross, many of the same rules apply: