I'm not sure I know exactly what you mean by "traditional roster" in this situation breh
Simmons is a NBA small forward, that has to play 4 because he's literally allergic to shooting. You can't have a team that has players that play traditional roles with him on the floor. You have to have a do-it-all garbage man 5 because Simmons isn't a rim protector. He can't shoot so he has to have the ball in his hands to be effective, which means that 9 times out of 10 you don't want to have a ball-dominant guard on the floor, so instead of having a PG run the show, you turn your guards into 2 shooting guards. And because of how this changes the floor, you'll need one dedicated wing defender at the 2 or 3 to stop penetration because Simmons will give up buckets or FTs to attacking guards.
So in order to build around him now you have your PF (Simmons) playing PG, your PG playing SG, your SG/SF both need to be great shooters and defenders, and your C basically will be a garbage man. It's hard to craft a roster like that just to tap into the talents of one player. I don't see Simmons fitting into any roster in the NBA as is.