Tough call. Let's look at their toughest opponents for credentials. Peter Griffin has repeatedly bested the chicken although he's gotten roughed up pretty badly. Homer fought to a draw with Bart's charity worker but also took some beatings. Peter made a moat to avoid the Black Knight but on the other hand Homer let hobos get tired punching him before he took a swing and Drederick Tatum outclassed him. I will say Homer after a tenth round decision for two reasons: First, he can take a surgical 2x4 to the head and second, because he will grab a cinder block and chain in the eighth round. After figuring out that he shouldn't use them to attach to his nipplies he will take the ninth and tenth round. All other rounds will be too close to call.
Special group cage match! Every person.....excuse me, cat........for themself
Azrael (Gargamel's cat) vs. Garfield vs. Heathcliff vs. Sylvester vs. Tom
Rock Rock On!