A couple of tricks:
Send in suicide squads. Certain teams (especially Zader/EP lead or Droid teams) have a huge initial burst, but poor basic attacks. Mix and match your suicide squad with junk characters to try to draw out as many of the nasty skills as you can.
Abuse the random seed. With a given leader, you will always get the same results taking the same actions. Get 0/5 stuns from your EP? That's okay, just shift one of your basics earlier to another target and get a 5/5 stun instead.
Preload TM on 1-3 backup teams. I admittedly haven't had to do this for awhile, but when I was struggling in GW I did it regularly. Use nodes 1-2 & 4-5 to get your backup teams a bunch of TM without really losing any protection.
Run a stall squad. For a long time my GW team was Old Ben / Daka / RG / Lumi / Lando. Painfully slow nodes, but this team could basically take on any team in the meta without losing a single character. This team took so many bogus actions (Old Ben basic, Lumi basic, etc) that I could switch them around and manipulate the random seed to get maximum stuns & dodges.