The following post contains spoilers for Puyo Puyo Tetris.
Though not a extreme fan of him myself, I have seen people online simping for him and after overlooking the tropes, I have come to the conclusion that he is indeed, to some degree, a sexyman. I have thusly made a Fandom account just to post this.
Ex is the current Keeper of Dimensions, the former Tetris King, previous captain of the S.S. Tetra, and the true father of Ess. He represents the crossover between Puyo Puyo and Tetris. (Taken from the Puyo Nexus wiki: https://puyonexus.com/wiki/Ex )
Source: Puyo Puyo
Aliases: Keeper of Dimensions (Given Job Title), Keeper of Dumb Suspenders (By Ess)
Class: Either Safe or Euclid, I browse the Japanese and International fanbases for the series and I see more simps in the Japanese one than the International one, with International simps being much harder to find, contained in their own corner of the internet.
Angst - After, for a unexplained reason, getting the ability to travel between dimensions (See "All-Powerful" Trope), he was forced to take on the job of being the "Keeper of Dimensions", putting him at the edge of space-time and separating him from the rest of his crew.
Because of the fact that he was now at the edge of space-time, he no longer had belonged to any world, and thus others would forget about him if a strong enough bond was not kept. This has caused his own daughter to forcefully try to forget about him due to the trauma she faced of him leaving her. (Yes, I myself realize the inconsistency in this. I'm just stating the angst lore of this fictional man here.)
DILF/GILF - Though his age isn't specified, just look at him. That's a old man. Also, is a literal father, to Ess.
Quotable Catchphrases - Each character gets their own set of chants that set off whenever you chain puyo or clear tetrimino lines, so there's more than enough to spare for Ex, but I've especially seen fanart use his "Rotation X" line.
Father Figure - As the description for this trope says, there's people who are aware of the simps, but just want him to ask if you're winning.
Intelligence - Built a whole robot just to take care of the crew while he was gone, also he just has the vibes.
Johnlocked - Specifically with Satan and Tee, both being extremely popular ships with him in the Japanese fanbase, and I haven't really seen him be shipped with anyone else, outside of a few crackships with Ms. Accord.
Mysterious - Not much else is really known about him outside of what I've outlined in the angst trope.
All-Powerful - Has the ability to travel between dimensions, as well as being the "Keeper of Dimensions", to where he is tasked with making sure the Puyo Puyo and Tetris dimensions do not merge.
Theme Song - Though shared with Tee's boss battle, The End of Silent Conflict first plays during his boss battle.
Villain - The antagonist of Puyo Puyo Tetris. See the below trope for more details.
Technically Antagonist - Though he is the antagonist and the reasoning for the games' events, said reasoning was actually just due to his loneliness and depression, and he's actually a good guy.
Suitguy - The upper half of him is dressed in a pink bowtie, whatever that type of frilly shirt is called, and suspenders.
White Hair - Yeah.