After playing a decent number of SWSH matches on Nexus, here are my thoughts on the early metagame so far:
The new pokemon are actually extremely fun to use, and they're great additions to the competitive scene! I've especially been loving Rillaboom with a banded set, and Duraludon with a modest Shuca set. Sirfetch'd and Galarian Darmanitan are really fun too, and Corviknight is steel/flying that fits super well with momentum teams. Barraskewda is a menace on rain, and Cinderace feels like a more predictable but still good Greninja. I have so many more mons I could gush about but the dex itself has made some super fun mons to toy around with!
However, the format is extremely toxic with Dynamax. The mechanic is so broken that everything looks like a Magearna after 3 turns, and even after you outlast the dynamax it might often be too late if you've had to sacrifice too much. Bulky Offense teams are simply out of the question, as is Balance because every offensive threat can dynamax and shred through all defensive backbones after a single ounce of chip damage has been spread. I really only see 5 archetypes lasting down the road: Rain, Sand, Screens, Webs, and hard stall (even this might get snuffed out eventually). The metagame is also going to stale extremely quickly because games do boil down to whoever gets their best dynamaxer off first. The mechanic is extremely uninteractive and I felt myself want to abandon this generation altogether multiple times while laddering LOL.
Keep in mind, the game isn't even out yet so nobody should really take action in terms of metagame management for a bit. But if it were up to me, I would straight up quickban dynamaxing. Doing so would actually allow for a ton of team archetypes to be viable again, and increase metagame diversity in the long run. If this is done alongside a Shadow Tag and Arena Trap ban, I don't see much requiring a suspect test down the road in a dynamax-less Galarian metagame (maybe Excadill, big emphasis on maybe). Seriously, a lot of these movepool changes for the Galarian Dex are really well balanced! But it feels like they didn't account for dynamaxing at all, and it really feels like the mechanic was intended for in-game playthrough purposes. I sincerely hope the mechanic gets the fuck out of competitive play.