I generally don't have to kill their swampert/meta/skarm to unleash ddtar. Though claydol definitely makes me want to cry when i see one so i might put in hp bug on ttar.
About the spikes comment 3 of my pokes are immune to it and i don't really see how forry/skarm are going to set up on anything on my team.
I do like the idea of putting spikes on the team, but i hate skarmory and forretress, i tried using cacturne and that was pretty cool. I might try cloyster at least he can explode and not get trapped