For me they underdelivered , and not with characters or reveals like that.
Online , despise some noticable improvements , is way more complicated (the battle Arena , I understand it , but only after watching it 3 times and comparing it to Sm4sh , and has some unanswered questions such as when I chose my rules , if squad strike available , ect...) and won't have a better connection. (They litteraly told us "Get a LAN adaptor" so I'm worried.)
Squad strike is a great mode that we didn't know the mechanics of. I shouldn't watch a leak video to understand how it work , I should watch the official stuff and understand right away with gameplay footage.
Spirits has such a randomized and FE Heroes vibe to it that I honestly kind of hate. Sure , all theses Spirits battles are very inventives... But it just seem that they weren't a good "replacement" for trophies. Sure , I understand why they were removed , but it was still an amazing way to encounter character you wouldn't even have before.
Now it's more like "Oh , this spirit is that power , too weak , don't need anymore. Here woomy XL , my Inkling amiibo , take it.".
I won't continue despise other problems (the lack of rewards that truly matter besides characters we already know , the removal of all-star and homerun contest , some gameplay elements , ect...) but my point is that I was disapointed with several aspects of Ultimate , and others people were too. Beeing characters or other stuff.
Were we asking too much with the grinch leak ? In my opinion , yes.
Was asking for ONE more character a la Ridley or K Rool too much to ask for ? No.
They ended on Plant , a joke character. We know they couldn't have someone like Geno or banjo in base , and why Isaac couldn't be playable. But they had , BWD , as an example.
Tl;dr : we're still customers buying a 70 dollars priced game , alongside 30/25 dollars of unknowed paid DLC.
That's why the "It's the best Smash game by far" argument annoy me , and it seem that It's often used as a way to say "Well , you can't get everything".
This isn't against you (I'm sure you said it as a way to keep positivity , wich is good) , and I don't want to derail the thread , but please remember that we aren't going to all be satisfied with Ultimate (Despise looking like a very good game) and that's why some people want their characters as DLC.
Not saying you said "You didn't get your character , get over it" but I think that you didn't know a lot of people wich weren't satisfied with the game.
Anyway , Sorry for the long post , I'll try to stay more on topics for future posts.
I think that using the original sound effects from SMRPG would be a great way to make him stand out rather than a voice.
Especially since SMRPG timed hits sound effect have a very satisfying feel to it. And since he's pretty much a retro character , I think all theses sound effect will add to that retro charm.
But not gonna lie , hearing him scream "Geno Whiiiiiirl" would be epic.