I think V-Tamer. Especially with Tai, they showed how the two of them worked together on a tactical level.
Maybe Fusion aswell. Mikey and Anji coordinated well, and Jeremy did some sword fighting sometimes.
Though generally I don't like the kids getting directly involved in the action since it makes the enemies seem weak.
There was a lot of that in 2020.
Now that I think about it, Ghost Game has a good balance. There's a lot of asymmetry to the human Digimon relationships, and since the battles are often spooky puzzles that are resolved peacefully, there's a lot of opportunities for everyone to contribute.