I suggest great kinchers for every melee branch, last I checked they had no protection against any damage type. On a side note, the only other creature they have this in common with is the yubo
Take a look at my list [thread=17276]here[/thread] if you want to find out which creatures have protection against your weapon of choice. Though it's a few months old by now and it's possible some changes have been made in the meantime, so let me know if you find anything incorrect.
Pikes have a good advantage in the ignore armor ability, which allows them to do decent damage to any creature. A pikeman stands a much better chance against a creature with high piercing protection than a sword- or axeman does against one with high slashing protection. On a creature with no protections however, a sword or axe will do much more damage than a pike.
I wonder why nobody uses maces. True, slow is pretty much useless, but when do you have enough credit to use anything more than accurate attack and increased damage anyway? Apart from that they do the same damage as axes, and unlike axes they aren't 50% resisted by plods.