Make comp like mystery heroes. Bear with me here
When you enter the match, you will be assigned a char at random, while still being in the 2-2-2 setup. So you can get anything. 2 tanks, 2 dps and 2 healers and you can get anything.
You get assigned the character and you can’t switch for the entire first round. So unlike Mystery heroes, when you die, you will remain the same char that you started out with.
When the second round comes up, only 2 people can change roles per team. So you, as a team, have to decide which people will switch roles. So you can iron out some bad combo’s or get people to play a char in their current class that they are better with etc etc.
What this will instill is that Overwatch is not only a team game, it’s a multi-character game. In my opinion, if you wanna get into comp, you are supposed to be able to flex. Ofcourse, you’re gonna be better at some characters than others, but everyone is struggling with that and it will force people to train on more than 3 characters what most players (in lower ranks) play.