Not objectively bad, but I’ve always disliked smash fan rosters (mostly “what if smash started today” or celebration of gaming history rosters)that only give each series one character. It just doesnt feel very creative to me.
I tend to think the opposite, that having a ton of the same series is possibly an indicator of limited experience/knowledge, and I like reaching further into VG/Nintendo history to see what could be done. I do also try to mitigate the other issue sometimes by having a series be represented by a villain or very prominent side character. But a roster like this that has like 8 Mario characters, 9 Pokémon, 5 Kirby characters, 7 Sonic characters, 5 Street Fighters, etc. isn’t gonna be as interesting to me as being able to pull in Sukapon, Andy, Lip, Ray (Custom Robo), a Rhythm Heaven character, etc. or Peashooter, Centipede, Carmen Sandiego, Tetromino, Parappa the Rapper, etc. These are more so examples.
I feel similarly about overly focusing on just platformers and JRPGs, and to an extent, only focusing on Japanese or American preferences (admittedly biases/experiences can come into play), but it’s also a tough balancing act.