I'm not sure what the pugs gear was (I was on thm) but he was eva tanking. It happened as an accident at first when we had a gla and a pug both in the pt and the gla went down, the pug stepped in and finished the second half successfully so we decided to try it with pug from the beginning, and it worked. I can see if I can find out tho what gear he was wearing and if he was using any materia.
Pug does take a few more heals than gla of course but also gets hit less, the damage output is higher so Ifrit will go down faster which can kindda make up for it. I'm convinced we could kill him before he can hellfire but we havent tested it yet. I'm thinking 5 thm, 2 con and a pug tank could do it if everyone was on their game. Closest we have come is getting him to around 30% health.