Actually, no it wouldn't
because, then you could choose the same partner for a leader, and get the same results (almost same results)
so if you need to fly, you just pair tails with a leader
if you need to run fast, you pair sonic up with any leader
etc
so it wouldn't bring much variety, if you were to do it by leader, then you may as well just have one individual ranking for each level, and that would just be the fastest time with any pair.