Whether it be an SDChomp, or any other variant...how do you take care of him? It seems like every team out there is either Chomp or Mamo weak. When a "wall" takes 80% or more damage, what's left out there?
I don't know how Vaporeon switches in with no problem at all against Mamoswine. Earthquakes that are Banded are going to 2HKO Vaporeon, I'd call that an un-reliable way to deal with a thread (best not say counter as the title is clearly deal with).
How do I deal with Garchomp and Mamoswine?
Let's say that my team is defensively based, I'd have it packed with Garchomp cover; Bronzong, Gliscor and Cressilia, with these 3 on the same team, for instance, I have the nescessary Pokemon to stop Garchomp effectively to halt it before it has chance to sweep. That's not always the case; I can't rely on Garchomp getting lucky, where as before I could effectively rely on the combination between the 3 Pokemon stated earlier to stop all Garchomp. If I'm confronted by an opposing landshark when using a team that's offensive but more vulnerable to my opponent's Pokemon, then I must use Pokemon that are faster to clear it away (un-reliable, yes, but it deals with it providing they're caught out).
Mamoswine is fairly easier to deal with than Garchomp, reason being it's moveset is alot easier to predict. I know for a fact he'll have Earthquake, and most likely Ice Shard. I just need one attack from him to know the set, item and speed. Them 3 are what I look for, and then I deal with him accordingly.