QFT
This is the best mindset to have.
I honestly believe that Ridley was selected as a playable character for Sm4sh, and for one reason or another that decision was changed.
Ridley has a complete moveset, right down to the edge grab. He has a character stock icon. He can even be KO’d the same way as a playable character. He was built from the ground up exactly like a playable. Even his render looks as if it was made smaller and then enlarged. I also think this is why he was teased with his shadow—they were still working on him as a playable—and that’s also why I think it was so late before he was revealed to be a boss (because his role changed during development). Eventually, Sakurai and his team felt that they couldn’t make him work to their liking, or they just liked how he worked as a stage hazard better, or for some reason the 3DS couldn’t handle him.