personally I think terrain teams are more of a gimmick, kind of like trick room, so I wouldnt recommend using oneOn a Psychic Terrain team, should Deoxys-A run Extreme Speed or can it be replaced with another coverage move? It's been tough choosing between Ice Beam to handle Yveltal or Knock-Off to handle bulky Psychic-types like Solgaleo and Lunala. Psycho Boost already OHKOs most Dragon and Flying-types under the terrain boost, so it seems Ice Beam is solely for Yveltal. I assume that Psychic Terrain will be up most of the battle, which would render priority useless most of the time.
Thanks in advance!
but as for the set, I'm assuming you're running LO instead of focus sash+rocks, so I'd probably go psycho boost, ice beam (more for mence (you shouldnt really be staying in against yveltal with deo-a), superpower, and knock off
you could also substitute knock off or superpower for extreme speed, you might want some priority on it if your only means of speed control is psychic terrain