I beat it (on intense difficulty with no items, set mode) with a very particular team. I led with bastiodon who proceeds to stealth rock turn 1, the opponent switched out the shadow pokemon turn 1 to the poke is a physical attacker and knows earthquake (forgot what it was). I then switched to rotom wash and will-o-wisp'ed it. I then switched to incineror for the intimidate. I then switched to blaziken and spammed bulk up and subsitute (with a lum berry for the hypnosis). I then switched into a swampert after enough bulk ups and with a substitute up such that the opponent did NOT break marshtomps substitute. Marshtomp then proceeded to sweep everyone until nagandiel. the nagandiel can 2 hit swampert, but because the substitute was still up, swampert could get 3 hits in and break the shields before fainting. That combined with the stealth rock damage was enough for priority attackers on my team to be able to wear it down with gem boosted stab attacks (including running dark gem on the previosly mentioned rotom-wash with sucker punch). Finally I was down to bastiodon and managed to finish it off with some (very weak) heavy slams. Very very tough fight, but beatable. Now I am stuck on the next fight T.T