Fossils in general have always been plagued with odd text and still more odd Pokemon that they evolve into. Very rarely will a Fossil Pokemon be ran because most of them suck to begin with and often are not worth the effort to bring out.
Anyways, Armor Fossil has great stalling potential if you are good at flipping heads, but since they now count as a prize if they're KOed, not such a great idea for stalling unless you are using a double-headed coin. Back in the old days before they counted as a KO, this would have easily been ran in 4s with Wailord EX or Politoed EX. But now days, completely pointless unless you're using Bastiodon, who I don't recommend you use anyways.
Modified - 1/10 (No point in this card except for Bastiodon, who sucks anyways. If they had the old Fossil rules still, it'd be better for stalling)
Limited - 2/10 (Even if you could get the Evo line out of the booster packs, unless you're packing Fossil Excavation with it, I highly recommend not running a Fossil line)
Unlimited - 1/10 (Base Set Gastly is better)