No one's Tier 3 is based on "conquering the universe"; Tier 3 comes from Lumas having the ability to transform into galaxies and also having the ability to transform into Power Stars and Grand Stars. And Grand Star Powered Bowser being able to give birth to entire galaxies; his Universal Black Hole is
Low 2-C, but Mario defeating that is PIS. And also, we aren't quite saying Mario scales from the high end feats of the Power Stars, only that he at least scales from the lower to medium borders. Luma transformations range from
Planet level to
Star level to
Large Star level to
Galaxy level. There are also plenty of Tier 4 feats from the Power Stars in Mario 64. And on top of that, there are plenty of Tier 4 feats regularly performed by Mario characters in the Yoshi games. If even Baby Mario characters have Tier 4 feats, imagine how much stronger than adult selves are. Especially in Yoshi's Story were Baby Bowser has
this transformation of Yoshi's Island into a pocket reality with
a starry sky.
As for the
Massively FTL+ speed feats, Bowser tagged the Starship while it was in the middle of traveling at intergalactic distances. That's
Massively FTL+ combat speed right there. And everyone who can defeat Bowser one on one would scale; that includes all the important Mario characters such as the seven Star Children; Mario, Luigi, Peach, Yoshi, Composite Wario, and Composite Donkey Kong. Daisy, Toad, Toadette, and many other characters can also defeat Bowser in Mario Run. Mallow and Geno are also comparable to Mario and Bowser and fought Smithy. Other underdog characters such as Midbus, Rawk Hawk, and Waluigi will just scale from the more casual characters
FTL feats. And there are multiple other
Massively FTL+ speed feats in the Mario Party games that are comparable to that one. The Raphael feat would double as a Millions of C; which is significantly lower, but still in the border. And Zeekeeper also has another
Massively FTL+ speed feat; but his is incalculable and would be in another league if it was.
This also goes without saying, but none of the mooks scale obviously. And I will say that Base Mario's numerous Tier 2 feats are all outliers. But the Tiers and speeds will remain the same for now. And if anything, there might be the possibility of
4-A base forms returning given the multiple feats. I also agree with DOW on some of the other details.