I don't have an alternate nomination for Dan's team - Sakura and Blanka seem like great choices. By contrast, I had a tough time with choosing Ryo's team - there's Robert, King, Yuri... However, I think I found a concept that stuck with me.
TEAM ART OF FIGHTING
Ryo Sakazaki, Mr. Karate, Marco Rodriguez
Three generations of Kyokugen Karate masters, ready to demonstrate their skill and shamelessly promote their school of martial arts! (I went with Mr. Karate rather than Takuma due to Mr. Karate's resemblance to Dan's deceased father, at least if Super Puzzle Fighter II is any indication)
...it just hit me that, in a weird coincidence, every SNK team that I've submitted so far has had a Garou: Mark of the Wolves character in it, even though I only played Garou on the Switch and haven't played a ton of it. I'd say that the trend probably won't continue, but I can think of teams for at least two more characters from that game.
For reference, in Capcom vs. SNK 2, the grooves were:
C - based on A-ism in Street Fighter Alpha 3 - three super bars, and you can cancel level 2 supers into level 1 supers
A - based on V-ism in Street Fighter Alpha 3 - custom combos allow all normal and special moves to cancel into each other, ending with a level 1 super
P - based on Street Fighter III: Third Strike - allows for parrying
S - based on King of Fighters '94 - you can charge your super meter and spot-dodge
N - based on King of Fighters '98 - you can use some of your meter to temporarily give yourself a 20% damage boost
K - based on Garou and Samurai Shodown - a rage meter fills if you take damage or perfectly block, giving you a big attack and defense boost once it's full.
There's likely more to it than what I'm describing; I'm just summarizing what I see online
(I'm not sure if I'll be able to come up with a Groove list of my own; I'm not familiar with the competitive side of fighting games, so I don't know what would be balanced)