Literally every team has got a counter. No matter which and thats the thing...thats why the best defensive is a superb offensive. Thats why the Imp/JTR teams are upstairs and rex their counter right next to them.
An extremely fast Phoenix team with shield mods and all zetas can be very difficult to fight against. Also an extremly fast NS team can be a pain - but everything has counters. So do 3 tanks as they do literally no damage and Nihilus doesnt care if you got 10k or 130k...you are dead afterwards. Wampa will enrage after 3 minutes and also one hit the tanks.
Speed is your real factor which makes your team tanky - as no damage from 1-2 opposite player means you survive and they die even quicker.
Even Kenobi with 100k shield wont bring you anything if he just sits in stun and doesnt provide the group with foresight/debuffs and his group attack - speed, speed and speed is the key. Be faster and dispatch the opposite before they can build up their attack chain.
If opposite team has no aoe dispeller acolyte + zombie will be timeout. Can do a nute gunray team against people without aoe dispell with acolyte, zombie, princess and last one i forgot...they simply stealth behind the zombie and kill you from behind. However b2, baze and sion will just wipe them =) and again we got a counter...
Only speed mods bring you to your aim further as you can beat even counter teams just by being faster (i.e. your imp is faster than rex, or chirrut...you will crush them)