Moxie is a god sin among Pokemon. I can believe that your Gliscor didn't faint in one blow from 2+ Dragon Claw. Regardless, Gliscor's def will reach 286 with no EV investment, more than enough to survive a blow like that period.
When I saw Ferrothorn come out, I said to myself....and here comes the wall blocker, but I laughed so hard the moment I saw you smash that thing to pieces with Gyarados! Bad move on your opponent's end, since he chose Leech Seed oppose to Power Whip.