I unironically believe Bubsy would be a better choice than Byleth. let's go through the reasons:
-He inspires some sort of strong reaction other than a sigh and a quiet "god dammit"
-He represents three notable periods of gaming history: the mascot craze, the rough transition to 3D and the nostalgia boom, as opposed to representing just another instalment in a protagonist-swapping series that already has tons of Smash rep
-While his design isn't too unique, he is instantly recognisable among other characters of his kind
-He could have a stage that isn't just walk-offs that sometimes get hard to reach platforms