Jotunn will one-shot any Barricade, which allows you to swap to your Primary while the projectile is in flight and able to easily hit the Guardian(s) behind it. Cloudstrike also would be a great counter as usually the player head is exposed and if a team is bunched up behind it, they would also be hit. Failing that, most Hakke weapons with the Origin Trait can quickly remove a Barricade and is one of my favorite Foundries for PvP due to Turrets and other spawnable objects.