(Just like my DK Rap rip, I gave this the improved alignment treatment, so hooray! It isn't as painful on the ears as it was before!)
Originally, I was planning on having Wolf be Leffen. That seems like the most obvious choice, but eventually I decided on Chillin being Wolf instead, for a few reasons:
Chillin is the one who originally called out Leffen, just like how Wolf is the one that approaches you and proposes a duel between you and him in Star Fox Zero.
Chillin is the one rapping this, not Leffen.
The line "I'm the underdog, so place your bets." Dog. That opportunity was too good to pass up.
Leffen is the one that beats Chillin, just like how the vs. Wolf mission isn't considered complete until you beat Wolf.
Last, and obviously least, Leffen's face kind of looks like Melee Fox's. It may take a little while to see at first, but once you do, you'll never un-see it.