Needless to say, spoilers.
On the final mission, your crew breaks up into teams of 2. The teams are:
Matt and Asha
Pierce and Shaundi
Ben King and Johnny Gat
They are picked for 3 different tasks. Does it matter which team does which task? Can I pick 1 team for multiple tasks?
Best Answer
One of the main differences in the Grand Finale mission that depends on which team you chose are dialog changes with the homies. Each team has different dialog for each of the mission parts. There are no significant gameplay differences that I noticed.
In the second part of the mission, in the part where (quoting Saints Row Wiki) "things from those homies nightmares come through but are friendly" - this will depend on the team you chose. It's not a big effect on the gameplay though, as you will leave that area shortly afterwards for your next objective.
Also, a mission part might be easier depending on which homies' loyalty missions you have finished (which homies have been transformed into their super-powered versions in the simulation). Super-powered homies will make finishing a mission part a little bit easier.
If you haven't finished all loyalty missions before starting the Grand Finale mission, IMO, you should prioritize choosing the super-powered homies that you currently have for the second part, and then the first part. In the third part, your homies will not be using their super powers, even if they have them. While the first part does not really require much from your homies (they will mostly just be driving a vehicle).
You can only pick one team per task / mission part. Once chosen for a mission part, a team can not be chosen for another mission part. I recommend saving before starting the mission, if you want to replay the mission parts with a different team.
Game Ending
Another factor that could affect the outcome of this mission is which homies' loyalty missions you have finished before playing the mission (rather than which team you chose). Because about this mission's ending...
Source: Saints Row Wiki, "Grand Finale - Trivia"