Sportacus VS Pepsiman and Waluigi VS Robbie Rotten goes unbelievably hard. Not as joke fights but as death battles with comedic tones.
Sportacus vs Pepsiman is also hilarious because of how it likely goes down.
They don't know about each other, but if Pepsiman decides it needs a ranged attack or to put some distance between himself & Sportacus or to blind him or something.... He could spray some Pepsi.
Although, IDK if Pepsiman's ever done so in-character, as Pepsiman might see being sprayed with Pepsi as something that can only go well. Refreshing taste & energizing through sugar & caffeine, etc.
But if he does, Sportacus might be in trouble....
Weaknesses: He does not have any combat experience and is strongly against violence. Very peaceful and pacifistic. Rather naive, as he has easily consistently fallen for Robbie Rotten's disguises. "Sugar" (Will pass out if he is exposed to "Sugar", although he can be replenished with Sports Candy).
Sportacus admittedly, has shown good reflexes & acrobatics, so he might be able to dodge, if he thinks to. (IDK how often he's been tricked into consuming sugar, but it's an in-universe known weakness of his Robbie will readily exploit when it's on his mind.)
& unless Pepsiman can become exhausted by spraying Pepsi or run out of Pepsi, then Sportacus at best, has to rely on a finite supply of Sports Candy vs potentially unlimited Pepsi.
To his credit, Sportacus DOES tier-stomp Pepsiman, IIRC.
But the mental image of the fight being Sportacus wearily crawling on the floor in lethargic agony, & desperately trying to reach some "sports candy" (fruit or vegetables.) half the time because Pepsiman sprayed some soda at him...
& then Sportacus doing over-the-top super gymnastics the other half....
It's just hilarious to me.
Not to mention, depending on how severely it weakens him, it could totally flip the script on who stomps who.