Okay, some of these guys are dead today, BUT if it were live action:

Strongbad should be played by El Santo, but then I think that's where the brothers chap got the idea for him, anyway. (must be MST3k fans)
http://imdb.com/title/tt0055408/

Bubs should be played by Scatman Crothers of "The Shining" and Hong Kong Fooey Fame:
http://imdb.com/name/nm0001079/ Given the fact that Cruthers has been dead since the 80s, he won't have to fake the blue pallor.

Marzipan? That's easy Cindy Sheehan should play her. This should be an improvement for Cindy however, since Marzipan even cares for a dead phicus. Maybe playing this role, will make Cindy care enough to finally put a headstone on the grave of the son she supposedly is still mourning.

Pom Pom should OF COURSE be played by Michael Moore, but they will REALLY have to pay the girls well, that are supposed to hang around him.

KOT should be played by Colonel Sanders, though it might put KFC out of business (is that a bad thing?)

Poopsmith will have to be CGI since I can think of no one in person who would do his job.

StrongMad would, of course, be played by Arnold Swartzenegger, in his Terminator/Commando days. Of course Arnold would have to take some acting lessons to be as expressive as StrongMad. Arnold's not quite as in shape now. Kind of hard to hit that Nordic Track when you have to run a state.

HomeStar would have to be played by no one else, but Bill Mahr. No one else is THAT stupid while thinking he's really smart. The role was made for him. (this is the guy that once compared retarded children to dogs) He would have to take anti-total JERK lessons to be as nice as Homestar, but in the brainless dept, he's a natural

The Cheat would have to be played by Eddy the dog from the Fraiser Show. The Cheat would have to be dubbed by Eminem. Just as squeaky, and just as intelligible.

Trogdar would have to be played by every idiot in Detroit who burns his own town on "Devil Night."

There is only one person white enough to play StrongSad and that's Michael Jackson. Michael will have to gain weight for the role, and gain a nose. Other than that, keep the kids away, he tends to hang them out windows and give them "Jesus Juice."

Homesar would have to be played by Bill Mahr in a double role that will really stretch Bill Mahr''s ability to be anythig else, but a jerk, for the reasons stated above.