Are you allowed to use an account that has already played skyblock for a while or do you have to buy a new account or reset your stats

Depends for what but i would say new account for mostly everything (if not everything already).

Like every category except for the races has to be on a new profile. But you don't have to buy a new account, you should be able to make a new skyblock profile via the nametag in the skyblock menu

hey what's up Yuidesu, you called me poor on my stream yesterday

you should be able to reset with the account delete, there would be no reason to have an entirely new account just for a run that might fail