Simple enough, just periodically allow a player to get a character they don’t own for a “trial run” so they can play as them for a bit and see if they would want to get them or not. Maybe even restrict it so that they can only use the character in Training, Practice, and Versus CPU (if that’s a mode in the game, I forget) or something.
I know that that’s the point of the free character rotation but the rotation doesn’t happen all that fast and it doesn’t really go beyond the first couple Season 1 characters, from what I’ve seen.