My setup for 1-3:

Top: 2 units (speed;anything is fine). Just make sure that the 1st unit has 40-45k+ BR just enough to solo the first mob before dying on the boss. The 1st unit should also have a higher turn-order and a minimum of 400 speed so that the 1st unit will be the first one to step on the arrow-node, while the 2nd unit goes to a boss.
Middle: 2 fast units (speed; anything is fine but if you want a second shot on the rng then make them fast too)
Bottom: 1 super fast unit (speed; 650+) pray the unit goes on the middle rng-node

I tried doing several other setups but it always ended prematurely because the unit on top reaches the boss even before the unit bottom reached the pest behind the rng-node at the bottom lane. From top-middle-bottom, I also tried 0-4-1, 0-1-4, 0-5-0, 0-0-5 to rely on my "luck" but all ended way worse than my tinkered setup above.