Finally was able to nail down 3 medals on 12-5 after changing my strategy from running balanced teams to running stacked teams:


Used this team setup and placements:



Team 1 - High power, strong units. Main role is to sweep the later mini-boss nodes and kill the final boss.
Team 2 - As strong as possible without making team 1 weaker. Main role is to kill the first mini boss and weaken/kill as much as possible afterwards.
Team 3 - Moderate strength team. Main role is to kill of the first 3 normal pest nodes, then act as a meat shield for moving pests.
Team 4 - Fast team. Main role is to tank moving pests for team 1 and helper team, will usually die in a fight but can sometimes finish off a weakened enemy.
Helper - 50k+ power was what usually worked for me to ensure at least completing the map. Main role is to clear later mini-boss nodes and weaken the final boss.

I had a bias towards helpers with strong slice/pierce units since the units on the map are weak to those damage types (especially slice). The basic idea is to clear out the first section while keeping your strongest teams from taking damage from the moving pests, then have them move in to clear out the second half of the map once the other teams have taken out the moving pest nests. Ideally, one of your sacrificial teams gets to this position:

so they can take out the string of nests before the final boss. After that it's just spinner RNG, since the stacked team can wipe out the mini-bosses while taking minimal damage and should be able to take out the final boss as long as the helper can weaken/kill the caterpillar boss.