[Question] How does wintrading work?

[malkal]

Thinking of gathering a few friends and wintrade a few hundred rating for ourselves. But how does it work? Do you exchange 1 win-1 loss and just go back and forth? Does one team get to the desired rating, then tank it to the other team? Wouldn't that defeat the purpose? How does this exactly "exploit" MMR? In the RBGs I did last season when we faced a team at our rating, we would lose more rating than they would win... So wouldn't it eventually just bring both groups ratings down?

Any help? (P.S. I know how to get the groups to queue into each other, I'm not asking about that)