As far as I know, the movement doesn't mean that it's doing a melee attack. If the main job is ranger, it should be attacking with ranged.
Most pets are weak to start with, and will lose most matches till their FP skills can match those of the AI's. 65 FP is kind of low, but not a real limiting factor. My wivre only had 60 to work with, and destroys 95% of the mobs thrown at it.
I don't know the level of your pet, but it almost sounds like you power leveled it to 50 in diablos without any skills and are expecting it to kill the champion...
Not gonna happen.
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