So, those of you who either don't care about spoilers OR have already completed the game may have learned that Colress is indeed present in PKMN SuMo.
SO his appearance has changed quite a bit, likely to keep him arrival on the Down Low, but Why?
I have a theory that Colress is NOT ONLY a former member of the Aether Foundation, but that he is also
Lillie and Gladion's father.
For one, when Colress was in Black and White 1 & 2, he was studying something very specific, unlocking a pokemon's maximum potential. A Quote from Bulbapedia states as much
"Oh, excuse me! I am a scientist. My name is Colress. The theme of my research is: "Bringing out the power of Pokémon." Bringing out the power of Pokémon! Is it possible to bring out their maximum power through the bond they share with their Trainers? Or is there some other, different method? I'd like to test my theory by battling with you. Do you find this acceptable?"
He was also studying how to allow Pokemon and people could communicate, again bulbapedia source "Colress mentioned his next project will be a device that allows Pokémon to communicate with people."
SO this leads me to believe that Colress had a hand in creating or designing the Rotom Dex, being a device that allows Rotom, a pokemon, to directly speak with humans something he himself said he wanted to work on.
This also leads me to believe that, why would Colress be researching pokemon power? surely it's not for no reason. It's because of the Ultra Beasts. The divide between Lusamine and Colress is simply this, He wanted to achieve this by unlocking the potential in normal pokemon to defeat the Ultra Beasts, while Lusamine wanted to create an artificial pokemon to do the same.
Why he was working with Plasma? Easy, learn about the legendaries in Relic Castle. Why was he mentioned to be in Kalos? Wanted to learn more about the power harnessed at Geosenge with Yveltal or Xerneas. Why though? Because he needed to know the potential of pokemon that can defeat god like beings like the Ultra Beasts, they were dangerous and needed to be understood or controlled. We also know for a fact Faba doesn't leave the Aether Paradise often, stating that he is "it's last line of defense" and Wicke had to be around for Lillie's statement about Gladion abandoning her to be true. Lusamine was too obsessed with the Ultra Beasts to leave, meaning a fourth researcher HAD to be involved.
It would also explain why Gladion seems to be waiting for someone in his Hotel Room on Route 8, who you run into just after encountering Colress.
You can draw more parallels to his "former" aether foundation status, with his original outfit in Gen 5 versus the aether foundation clothing. Believing the connection to RBYG version, Colress fits perfectly as the Blue to their Red, Green, and Yellow. Not to mention, Colress has the same eye color and hair color has Lusamine and the children, minus the blue streak of course.
This leads me to believe that Colress was a former high ranking member of the Aether Foundation, left to study Pokemon Potential and gather information in other nations on their behalf, but ultimately left after disagreeing with their methods due to what he learned in BW/BW2. He created or helped to create the Rotom Dex, and fathered Gladion and Lillie. This leads me to believe personally that Professor Mohn, now the runner of Poke Pelago, is their uncle and that Poke Pelago is a series of islands created by the Aether Foundation in secrecy to monitor the progress and potential of Pokemon belonging to trainers. Not to mention the Poke Pelago - Aether Foundation - Colress connection is proven through Mohn being a former member of the Aether Foundation, and Poke Pelago not being accessible until COLRESS speaks to you. Even if Mohn was Lusamine's Husband/first husband, he may not be the kids father and or may have been her second husband.
I MEAN LOOK AT THIS RESEMBLANCE.
Let me know your thoughts on this theory!