I believe in Beat Box. 4 Special Moves, 1 Tuba Tuba. Nothing else matters.
Statistically he's terrible, but his real strength is in spamming an unblockable BB3 with enrage. This means you want to max your moves to get their cooldowns as low as possible, and stacking almost pure damage stats as well, making Beat Box require quite a bit of investment. If you don't at LEAST have your Tuba Tuba maxed then he's going to not feel great.
Unfortunately, he has no meter control, so the hope is to blitz them before they get any real chance to respond.
I'm Diamonding him and Ora'Oraing my way to glory.
That being said, do not use Beat Box as Defense, he requires skill and finesse, or at least 1% understanding of how he works, which the AI is completely lacking.