Beat the Bomb Bot
Keep hitting the bot until he starts to explode. Next use multiple power uppercuts on him. If timed correctly you should defeat the robot without getting killed.
Beat the Kangaroo
Simply throw uppercuts wildly. As soon as he is about to throw something he should get socked and jump around again.
Beat the Second Boxer
Keep your guard up until he ducks his dead down by his waist. Wait for him to try a hook and immediately block it. If you're successful he'll be stunned. Take advantage of his condition with a punch to the gut.
Beat the Third Boxer
Whenever he goes down then hits you from the side do the red hand uppercut. The rest of the time block his moves.
If you beat every boxer without losing you will fight a secret opponent that looks like a cat.