I don't think the lack of 6v6es is in and of itself a problem. Just thinking back to the last League... Can anyone really say that they remember the finale for, I dunno, Luchabull VS Manyula? Most of the matchups throughout those 6v6 battles almost feel like just padding while we wait for the final 1v1 matchup that we're all there to see in the first place. I feel about the only way to get around that is if literally every Pokémon on both sides has been clearly established ahead of time and have interesting dynamics with the opponent they're facing which... I feel like at most you might be able to do that for one or two trainers. In the entire series. At the moment I guess the one that's closest to reaching this status in Alola would be Gladio, with his four Pokémon who have all been given at least some level of characterization, backstory, and some of whom have a dynamic with Satoshi's team... But even then, the battle between the two would likely just wind up being either a 3v3 or a 4v4 with largely irrelevant matchups for most of it culminating in another Midnight Lugarugan VS Dusk Lugarugan showdown. That is the rivalry we'd want to see resolved here, and while his other teammates do all have at least some character, the other matchups leading up to that final 1v1 could be literally anything. (Well, I guess Pikachu VS Silvuddy would also make sense as an "Ace VS Ace" kind of showdown.)