Recently game press released a sheet showing which mons were capable of 3 and 4 man aggrons, im trying to do a 3 man rayquaza, is there a sheet on that
It says it on the sheet that you should be able to do it with a party of 2 to 4 people. And 'how hard' it is depends on your battle party, and the battle parties your teammates are using. So until you tell us what yours and your teammates teams are, how on earth are we supposed to answer that question?
Pokébattler should help:
You can customizz the weather/moveset/attacker levels and more.