[Meta thread] Iron's PokeRole Adventure: The Skull Ruins

[Dragonstrike]

That looks like a excelent plan! Quetzal have Ice Fang and Thunder Fang. I could try to paralyzed/freeze him and with the bonus chance of Flinch him.

Again, you need to be powered up by the Helm for a move's secondary effects to directly do anything to Deoxys.  I don't recommend trying to Flinch or Freeze Cosh with a damaging attack.  If you're going to inflict debuffs on Cosh, try to stick with non-damaging moves.