First thing I want to know is where these pokemon stats are coming from since they haven't been officially confirmed yet.
Next is that if these stats and ability are legit, then out of the trio I think this one will be the best one to use. It has a good defensive typing with a few quad resists, good overall stats and good ability. It's offensive typing is good as well. The only problem is it's speed stat combined with it's weakness to stealth rocks makes it difficult to switch into things that it's supposed to potentially wall. I think that heatran, with more quad resistance and neutrality to rocks will outclass volcanian. Also, if this thing can get a recovery move than it would be better.
Next is that if these stats and ability are legit, then out of the trio I think this one will be the best one to use. It has a good defensive typing with a few quad resists, good overall stats and good ability. It's offensive typing is good as well. The only problem is it's speed stat combined with it's weakness to stealth rocks makes it difficult to switch into things that it's supposed to potentially wall. I think that heatran, with more quad resistance and neutrality to rocks will outclass volcanian. Also, if this thing can get a recovery move than it would be better.