Mad Clown is hard at first, but like everyone else, he telegraphs his moves. I remember my jaw dropping the first time I fought him cause he was so fucking hard.
He's A LOT like Bear Hugger, but harder. First, most of the time against other opponents you hold down the A button to do a strong upper cut when you have the special punch. But against Mad Clown, just tap up+A to do the rapid punch in his face thing. That works really good against the fat fucks.
After you knock him down twice, he'll do this thing where he'll keep punching you, but if you just block up as soon as he gets up and then dodge his back hand, it's not too hard.
As for the balls, he'll only throw two at once. Meaning you can avoid getting hit by either dodging left, right, or not moving at all. But as soon as he's done, he'll do this thing where he'll punch with both hands. Just duck and he won't hit you.
Like everyone else, he's easy as soon as you figure out his moves. He telegraphs his punches really bad, so as soon as you figure out what his dances and poses mean, he's easy as pie.
Don't worry, after him you get to fight Super Macho Man
And just so you know, you can't fight the last circuit unless your record in the three previous circuits is 4-0