This hype cycle has been far too filled with third party characters and absurd ideas for characters. Hearing people recommend Sans, Solaire, and Master Chief make me groan beyond belief. Nintendo characters or third party characters who have earned a significant reputation in gaming are the only ones deserving of a spot in the game and they need to have some affiliation with Nintendo. Bayonetta for all intensive purposes is a Nintendo character now, and Cloud represents long standing partnership between Square Enix and Nintendo. No, they don't open the floodgates for any character and their mother.
Most people just got on the Crash bandwagon because the N'Sane trilogy got announced for Switch. I have no problem with him being in the game, but I think most of his support came from what shouldn't amount to a huge announcement and the fanfare for Crash really wasn't there beforehand. Some people did support him, but I doubt there was any consideration of him prior to the March direct in all honesty.
New Pork City needed to come back since it was actually the perfect sort of stage for 8 player Smash, should have been in Smash 4 to begin with.
I get the idea that Mii Fighters coming back supports the everyone is here motif, but they always felt like far too large of a development sink in terms of how much effort got put into them. I didn't like how much attention they got in 4, and if I'd even got a single new character in Ultimate out of them being excluded I would make that trade in a heartbeat. Miis have practically died with the Wii U anyway, and it's not really "Playing as Anyone" They lack polish or excitement.
People need to stop with the relevance arguments. Smash is a celebration of Nintendo, and pulling out fan favorite classic characters that haven't been seen in some time is the ultimate celebration of Nintendo. Smash isn't exclusively an advertising platform as some people claim it to be, and we've seen plenty of minor and strange characters make it already.
Mario, Fire Emblem, and Pokemon can all get new reps as long as they're interesting and worthwhile additions.
Waluigi being an Assist Trophy isn't a huge deal. He would have been neat, but I don't think he's that important of an addition yet when characters like King K. Rool and Geno are bigger fan favorites that we've still yet to see.
Echo fighters seem to need to be very close to the original fighter in terms of how they play, so I think a lot of people are making crazy predictions about Echo characters that won't actually work. What most people are describing are semi-clones and are probably part of the thing they claim to dislike so much.