Having replayed both SWSH and SV recently, I have to say I really like the implementation of Kubfu and Ogerpon as DLC companion Legendaries (if anyone comes up with a shorter and snappier term for them, please let me know). It's a nice way to get you attached to them and their story, and it adds a great element of replayability to the main game once the DLC is released. It feels like a nice evolution of the concepts explored by both Nebby and Zygarde in SM, and is a great way to differentiate them from the standard late-game Legendaries. I was initially concerned that they'd be too closely linked to the DLC and feel out-of-place in other environments as a result, but Kubfu coming back in Indigo Disk pretty much eliminated those concerns.
I really like Kubfu's little training arc in particular: provided you start Isle of Armor during the main game, you receive Kubfu at Level 5, while Mustard's Kubfu at the top of the Tower is Level 30, giving you incentive to leave the Isle, embark on your League journey, and come back later once Kubfu is strong enough to take on the Tower. This element kinda goes away once you hit the post-game, since you'll just be shoving EXP Candies down its throat to hit Level 70, but I chalk that up more to awkward level scaling than anything else, and you still have to take on the Tower with Kubfu alone to earn that evolution. The option of a Dark or Water typing on Urshifu also lends it some nice flexibility depending on your team comp!
Ogerpon, on the other hand, comes at full power immediately - it already has Ivy Cudgel once you catch it, and you get all three masks instantly once you do. But with that power comes even more versatility than what Urshifu had - the different typings and stat boosts from Embody Aspect means that Ogerpon can do different things for different match-ups, condensing a lot of value into one team slot. It's pretty neat!
I do have a few personal criticisms - for one thing, I wish their scaling was more dynamic than it currently is. This is a criticism that can be broadly applied to Pokemon DLC as a whole, but I think it hits these 'mons the hardest; Kubfu always comes at Level 5 no matter how far you've progressed, and Ogerpon always comes at Level 20 unless you've gotten to the credits. EXP Candies do a lot to address any potential level gaps, but I think adding ~5 levels per badge would be a solid change. In Ogerpon's case specifically, I think they're too strong for how early you can get them - I wish that they had a pre-evolution ala Kubfu, or some kind of limit until you can progress farther in the game so they scale more appropriately like Kubfu did - maybe put Ivy Cudgel at a higher level, or hold out on the Masks until you get farther in Teal Mask. Lastly, this is a very personal thing, but I really wish that they didn't overlap with starter types. In Kubfu's case, it's only one of the potential evolutions that has Water to overlap with Inteleon, but it's more egregious with Ogerpon, who's a Grass type no matter what and can take on Fire or Water depending on the mask it holds. I don't think most players care about this, but I'll confess it really bugs me personally to have type overlap on in-game teams so I don't like the potential constraints. But overall, I think the positives significantly outweigh the negatives, and I hope this is a trend that continues!