I follow the above strat. Additionally, synergies are big. I either quit the match because I can't get any decent synergy in the first few rounds, or I get 1st place. You just have to keep playing until you find units that work well together and synergies you like.
My favorite strategies are:
1. Yolo poison + tactician (front: Torcine, Canictonis/Varani, back: stuff with tactician like Icefisher Stork or other poison units to complete the synergy)
2. Yolo pack mentality + tactician (front: Varani/Icefisher, Macauco, back: Colpach x2, Lupin/Grimalkin) (starts off weak, but sweeps the floor later)
Bad synergies are too many tanky units/healers. Stalling will only make you lose 5 points if you go over 20 rounds and you'll lose to poison.
Other companions I may pick (since you don't always get the companions you want, you gotta be flexible. I usually go for a tankier poison team):
Abyssal Thrasher - good for completing poison or tactician synergy and coordinate is nice
Pincher/Sparklequill - nice frontline unit if I want to complete a poison synergy + bleed damage
Other good poison units like Hydra, Lunaria
Grouger - if I want to complete the support synergy
Monstropod - mainly to go with Grouger to complete the support synergy, but it's a decent tank
What I avoid:
Weak passives/attacks like Piercer, Backstab, Patience, Berserk (dunno if it's actually good tbh)