A lot of forms get a skill that does unblockable damage, beyond bite. If you didn't get one in the forms lottery this time around, then it's understandable you're going to have trouble with very defensive melee types. It may not be enough against certain warriors even with substantial damage reduction, but them's the breaks.

Edit to add: I'd have to look harder than I care to for a polearm specific example, but I do recall going up against a few ragers with Nreykre who I hardly ever hit in combat. With proper prepping, gore spam was enough to fend them off almost every time.

My guess is that the fact that many shapeshifter forms have an achilles heel or two is by design.

Suffice to say, I'd be inclined to agree that as a shapeshifter with a form that isn't adequately suited for fighting battle giant polearm spec, there probably aren't any tactics short of calling a gang that are going to reliably swing the fight by a high enough margin to satisfy you.

For what it's worth: I bet you've played builds that made someone else think, "Damn, my build just CAN'T beat this guy no matter what I do." In some cases, that person may actually be correct. In others, they're just not being clever enough. Either way, I've always been under the impression that dilemmas like that were by design, especially in the case of a class where your build and therefore your range of tactics are randomly assigned to you in the first place.