This is a guide made by awol_lsd in the official forum which explains the two major builds of Warrior in Pet Forest - Dps Build and Tank Build. Each with the attributes building and the pets choosing and the skills choosing. Check below:

Play as DPS in full parties (instances) is different as strong solo. In instances you're running your Cactus and using your and your pets AOE skills to produce massive DPS.
But before boss your really should switch your pets as you won't have a mob to use your AOE against. so switching your Cactus to possession and Mushroom or ESM to attack will produce more DPS on the boss. No reasons I prefer the Cactus/Mushroom.
When you switch pets for bosses, skilled line warriors don't have much critical hit rate. so the Cactus with more dex being set possession provides more critical hits for your single target attack - it means more DPS over the fight. and Mushroom with his bite skill heals it some. so healer can focus more on healing players than pets.
if you play set on auto instead of manual then remove ALL things from your action bar OTHER THAN Chivalry and Rage Sweep. Leaving it default to Chivalry. Change Rage Sweep for assault while on boss and add Perseverance and Cross Chop when you get it. (the reason for this is Chivalry has a longer cooldown. so when it's set to default you will auto cast a random skill on your action bar. if the only skill is Sweep or Assault then your sure it will cast that. if you leave physical attack or skills not wanted for that fight, it may use that when not wanted. so remove them to avoid the possibility)