Every mob must be killed in the zone otherwise they will aggro when Wuoshi Aggro's.
Wuoshi has a very large hit box.
Wuoshi spawns a "Ancient Grovebeast" add at 75% and 25%.
Common stratey is to tank Wuoshi on the paddock to the far left corner of the entrance to the third floor. Everyone in raid should have Noxious Cure Potions on them at all times during this fight to save healers from having to cure people and stop healing.
Wuoshi has an AOE called Nature's Fury that is also a knockback. Your raid will want to joust this AOE as its range is about 50m.
Woushi also has a random root/stun/stifle/powerdrain that will turn your player into a tree root. It is a rather large looking root and needs to be ARCANE CURED asap. This happens very often to everyone in the raid. If you miss too many people your raid will soon have everyone turn into a root. Mages MUST help out with curing people they see that are a root ASAP. Because of Wuoshi's large knockback, if you are not out of range when Nature's Fury hits this knockback will knock your stunned players half way across the zone. Make sure people are calling out for Arcane Cures.
There will be a lot of running around in this encounter but groups need to stay together so people are within range of each other.
The second phase of this fight deals with the Ancient Grovebeast which must be pulled to a location away from Wuoshi's effects and to a place where the entire raid can gather in one spot to focus DPS.
Generally your Main Tank group will be the only group isolated much of the time. The rest of the raid must joust Nature's Fury and pull the Grovebeast far away from Woushi. Jousting as far back as beyond the bridge of the paddock. Wuoshi is a rather gimp mob compared to the other names in the zone. The main issue with this encounter is properly separating the Grovebeast when it spawns and dealing with it's mem-wipe in the process.
When Grovebeast spawns he needs to be pulled/dragged to the river as he has a nasty knockup. The knockup combined with the arcane roots spells trouble. So get in the river or under the ledges by the river. Properly seperating the beast is the trick. Illusory Allies from an Illusionist, the Coercers Amnesia spell and such will prevent much of the time from the Grove beast running back to the main tank group on his memwipe. Make sure your Secondary Tank is right up on Wuoshi to grab the beast the second it spawns (it spawns right under Wuoshi). Perfecting the seperation is the key to this fight.
You should not need more than 3 healers to keep your main tank alive. 3 healers for the Main Tank Group and 4-5 Healers for the rest of the raid depending on curing. Perfect the separation and you will win this fight.
Good Luck.