With Mr. Immortal being in his 60s here there'll be a different dynamic than in the comics if they do GLA (which I hope they get around to eventually). Also nothing to indicate his origin as far as I remember so he might still be a mutant (or more specifically Homo Supreme).
I wonder what they'll do with Intelligencia. I get that it's some kind of incel forum mixed with a bit of Kiwifarms, but I have to wonder how many (if any) actual Intelligencia members will be behind it. I could see it going 3 ways. 1. It's just the forum without any actual Intelligencia members behind it, though potentially it could have someone like Titania involved. 2. It's a plot by the Leader but he's working without any other supervillains. 3. It's a version of the actual group from the comics with multiple genius villains combining their intellect.
Though even if there is an actual villain group I don't expect multiple major villains to show up in this. Maybe they'll only allude to the larger group still being out there and they'll show up again in Captain America 4 or something.
As for the actual members:
- Leader is the one most people are probably guessing at
- Egghead and Klaw seem quite dead, so they probably won't be there.
- I'm not really expecting them to introduce M.O.D.O.K. anywhere before Quantumania so not him either.
- They probably won't make Doom a part of it either
- I think the Mad Thinker is the most likely if there's anyone besides the Leader. He's pretty straight forward so it wouldn't be a stretch to introduce him. Also in the comics he was involved in a lawsuit and his creation Andy/Awesome Android eventually started working for GLK&H with She-Hulk, so he'd make sense to introduce here.
- Red Ghost could be, though I think it'd be hard to introduce him properly + spend budget on his apes.
- Wizard is probably the 3rd most likely after Leader and Mad Thinker because he's also straight forward and
- Trapster (AKA Paste-Pot Pete) isn't really a staple member of the team, but for a comedy show like She-Hulk I could see it working to introduce him.
- Potentially they could add a new "bad scientist" type member to the team like AI Arnim Zola, Justin Hammer, Tinkerer, or Iron Maiden.