I'm honestly glad I got fixated on mixels/this silly bird again. If I was putting my mental energy into only the brawl stars fandom, I think I will die faster due to the sheer amount of drama/petty fights.
Im sure they just made whatever on the spot. The boxart for smb was probably made by someone at NOA (nintendo america) based on what they saw from the TV. It should be noted that smb sprites were first made on paper in-office in japan, and didn't seem to circulate outside there.