A.G.L.
Smash Ace
If it's a Dairy Queen rep then it's vanilla and choco.. XD Ok seriously, umm of course a DQ rep must have the DQ theme regardless of who it might be (Overture), You know, that track alone would be a huge leap for Smash. My second guess goes to the battle theme. Those two are the most recognizable.
Here are some examples. Orchestral, as I hope that's the case.
Overture (I'd love if they had Dai's though )
Battle theme
Sephiroth, well definitely his theme. You know of it, The One Winged Angle. I know of no other, and this one fills the list tbh. As for the stage, either Planet's Core or Nibelheim. George, I have no clue. If you haven't mentioned him, I wouldn't even know of his existence. Is there's a reason that might stop Square from doing that?
Umm, Banjo... Definitely Spiral Mountain. Most of the rest sound similar, and honestly to the annoying side. So I'd go for Click Clock Wood.
Lol Dairy Queen rep, if thats true I hope its a Mint Oreo Blizzard rep . Actually you know Calane gave some real insight for DQ music to be added to Smash.
So the 1st on your choice I agree is the DQ Theme.
The second and third music choices I would think would be.
Ocean from Dragon Quest 5
Go for Broke from Dragon Quest Swords
As for Sephiroth I think they could use the Forgotten City from FF7 Advent Children. I think they could use George Nibelheim since he isnt union. However not sure they would want Cloud to stay with a japanese VA and Sepiroth to have an english one. As for music he could come with if they do give him an Advent children stage then one winged angel advent children version. Also he could have the following two songs as well.
Battle in the Forgotten City
Those who fight Advent Children version
As for Banjo stage agree Spiral Mountain. For his music they would definitely put his main theme song in. I think they would put the Spiral Mountain song as its very iconic and for the final one I think it would be.
Jinjo Village from Banjo-Tooie