On the team you mentioned, there is no real abuser of sand. Garchomp's sand veil ability is something you can't really rely on. Instead, you should use an Excadrill with either a swords dance or rapid spin set.
Excadrill has trouble breaking past Skarmory, Ferrothorn, Rotom-w, and Manaphy. Teammates like Magnezone or Serperior help take these pokemon out so Excadrill can do its job.
Also, you said you were finding a sp.def staller for the team? I suggest an AV Tangrowth. This will give you a good water resist on the team, and with regenerator, it doesn't need a healing move.