yes that would be fair considering how original itis in the game so i will give you my Two cents on this idea and say we should do this. Although there is one exception to this and it is when your pokemon evolveI think you should apply this rule that I suggested in the shinnoh league
A player challenging the elite 4 must use the same team throught the entire challenge. Doing this will make it more competitive and bring an actual challenge to the league. As soon as a challenger is ready to go to the Elite 4 they must announce their team so the elite 4 members know the challenger is not switching.