I dont know if this is the best way to do it, this is what i think is a good way to clear the first boss
1. Have 4 range dps, 1 druid, 1 good tank, 1 mesmer (the mesmer can be the tank).
2. The 4 range dps go to the green circle while the group stacks in the mushrooms.
3. Evade when you see the blue attack.
4. Have 1 person pushing away the red bubbles.
5. Mesmer use time rift then elite skill to give speed to the party and also skills to give alacrity and repeat after time rift.
Doing this correctly you can clear phase 1 in like a minute even with exotic gear.
6. On Phase 2 team red and green stack on the mushrooms and either evade or push the atacks while team blue goes to the circle.
7. Must likely green boss will die first so team green can go help blue.
So you must have enough time to do the remaining phases
Still need to confirm this:
I dont know if the blue atack spawns at random time but if it isnt then you can time it so you dont use a big atack (like skill 2 of warrior) just to cancel it with evasion.