Regarding duo, what about the ability to change your partner but only if a certain criteria has been met, ie your partner has been offline for x amount of time and you are only able to change your partner to a brand new lvl 3 account with zero xp?
This makes it so in case your partner quit or de-irons you are still able to find a new partner but that partner needs to start from scratch, not allowing people to "freeload" by having someone with a beast account make you your new partner.