Alright, so I started doing Ifrit Hard Mode tonight with a couple friends. My first try wasn't the best - I was put on stun duty and needless to say I wasn't doing it well. But after the second and third times I had it down no problem. I was only stunning when Ifrit casted Eruption and ignored the Plume attack.
However, other people in the party were using abilities which stunned Ifrit. According to what I've read, each time you stun him it increases his resistance to subsequent stuns. I tried explaining why I was missing the eruption stuns (because I was getting resisted) but they continued to blame me for it.
So my question is this: is this information accurate? If other party members perform a stun, does it increase the chance that Ifrit will resist my own stun? Moreover, how do I explain this to party members complaining about the stuns?