It's not impossible without friend bonus, just very difficult.
I've done DM trio with best friends twice post-buff, once in cloudy, once without any boosts. The basic team you want is 6 maxed OR/DC dragons and a relatively fast phone for max reviving. Boosted faeries have viable DPS, so in cloudy we had one person use a full fairy team and they didn't have to rejoin at all.
Even without cloudy we put a fairy anchor into one team so they would naturally last longer and make sure we don't accidentally all relobby at the same time, which felt helpful. If the RNG is rough your Rays/Dragonites will just barely fire their first Outrages, they literally die like flies.