the solution is so simple imo.
they should allow Trios, Duos and Solos to queue in. if you queue as a Trio everything is like normal. if you queue as a Duo you get some sort of bonus like faster revives and an additional shield if you are near to eachother. if you queue in as a Solo you get 1 respawn and a sizeable movement speed boost.
this is just an idea from the top of my head, just spitballing the first thing that came to mind.
not only would this make fights more varied, but also instantly offer a good option for all 3 types of players. this way a trio, duo and solo would basically be like 3 additional sub classes in the game as each type of team would play differently, both to play as and to fight against.
as a trio it would be all about sheer bruteforce power of being 3 people working together. as a duo it would be all about fighting as a unit, staying close to activate the shield boost. as a solo you'd need to be light on your feet, surprise attack people that you caught being away from their team, storm in with your enhanced speed, take someone out, and back into the shadows.
I feel like that would be an interesting concept and a unique one on top of that.