Sakurai didn't screw around with the alts here: He didn't just give the people Ridley, he gave him the alts fans have wanted, referencing his appearances in games and artwork over the years, including Meta Ridley.

This is truly one of Sakurai's greatest blessings.

I think that the reason why Sonic only have diferent shades of blue is because Sega wants Sonic to stay blue in the smash series.