I beat the main part of the story, still need to find the rest of the Ogre clan, catch the loyal 3, and do Perrin's sidequest, but this is the team I ended up going with. Continuing on with my goal of using different teams for each of the stories in SV (and because all of my base story teams are level 100 now), I put together a new team for Teal Mask. For the DLCs I decided to drop my restriction of only using new mons so that I could use some mons that I haven't used from previous games.
First, I was hoping that Marshadow would make it in, but it didn't, so rather than hope it makes it in with indigo disk and waiting 3+ months, I just opted to use a raid ghost-tera Annihilape I had sitting in one of my boxes, naming Fauxshadow as my substitute for Marshadow.
Then, I saw on Twitter that the Sinnoh mythicals did make it in, and I had a shiny Darkrai from GO that I had deposited in PLA but didn't really use much of because I had beaten the game well before HOME connectivity. So, I moved this Darkrai over to SV (after having to do the runaround of placing a non-GO Darkrai in SV first -_-) and finally getting to use that in a playthrough. It was originally level 49 or so, so I used it most in the early part of the DLC since it was the lowest leveled mon I had for a bit.
Next, before the DLC dropped I had already decided I wanted to use Gliscor and Trevenant. I ended up getting them much more quickly than I had anticipated: the first day I went to do a 6* raid off toward the timeless woods, and on the way I ran into a Gligar that I added to the team. Then, it turned out the raid boss was a rock-tera Trevenant, which was pretty convenient because at that point I didn't know for sure if Trevenant was a wild spawn. (I was guessing it was, but hadn't checked to confirm). Plus the raid was close enough to the timeless woods that I figured it was practically like I caught it there.
I kept Gligar unevolved for a while, and even though everything was pretty high level it generally held its own, unlike a couple of other mons to be mentioned. I eventually evolved it after a battle with Kieran where my Gligar took down his -- felt look a good story beat that would warrant an evolution in the anime. :P Had to fly to Paldea, though, since I think the time of day is locked during the story.
The last two slots were the hardest to decide on. Other than Darkrai I wanted to use mons I got in-game, so while I had considered using hisuian arcanine if available in game, you can only get the gift after Perrin's sidequest. I was going to use the Chimchar I hatched from Jacq's egg, but eventually decided that I didn't like having 3 flying weaknesses and no resists. I ultimately decided to use Armarogue, even though I used it on my team star story squad, since I don't care for the team I used for that story and wanted a new head-canon team for Armarogue. I grabbed a grass-tera charcadet to use and leveled it up with candies. Like Gligar I wanted to level it up after it got a nice win in a battle, but it wasn't quite able to clutch anything out itself. It did well at keeping Munkidori under control with clear smog in the titan battle, so I decided "good enough" and I evolved it after that battle.
Finally, for the last slot I was really stuck for a while. I kind of wanted a water type, but none of the native kitikami dex species were appealing. I thought about trading for a piplup, but Empoleon felt more like an Indigo disk mon. I decided to try put poliwhirl for a bit, since I've been feeling lately like it deserved more mascot status popularity, but even at high levels it just didn't get to do anything without being ko'd, and I didn't want to evolve it so I decided it had to go. I briefly considered dropping my in-game requirement and catching Manaphy or Phione in PLA and transferring them over, but I happened to see the natdex mono-dragon team tweet from Smogon that had walking wake on it, and I thought "screw, I do like walking wake, and I caught it in game and never did anything with it. It's going on the team." One funny moment using it was when this big scary dino-mon failed to ko an Ogre clan's Ribombee with flamethrower, which quiver danced and took out Wake with a moonblast. :P
Overall I like how the team turned out. I have an idea of what I'll use in indigo disk, but that'll partly depend on whether raging bolt is available during the story, unlike Ogrepon and the loyal 3 here. I'm also curious about how much content there is in the "return to area zero" part of the story -- if it's substantial enough I might make a new team for that and maybe use ogrepon on it since we don't really get to use it much in teal mask.