Premade groups will only be matched in Battlegrounds against other premade groups, but if you are wondering about playing with your small group of friends, then fear not, as Senior Game Designer Josh “Aggrend” Greenfield explained that there will still be a small-group option. This will potentially be around 2-3 players, but that is still being decided.
Battleground Matchmaking was first discussed in Classic in Phase Two of Season of Discovery, when changes to matchmaking meant that premades were less likely to be matched with PuGs. This did come with a caveat whereby, after sitting in the queue for a period of time, the new rules would be ignored. We don't know if that will be the case in WoW: Forever.
