>>23248912HGSS had its own move tutors in the same gen that were payed by BP, also almost every Gen4 BF facility supported doubles and would have supported triples, if had the opportunity to do so, without lacking special gimmick clauses or systems. Crystal had only the Battle Tower and the fact that there was a BF place in HGSS with DPP leaders was already a huge gift to add to the Pokethlon. On the other side RSE also had at least the Battle Tower but Emerald introduced Hoenn the first Pokemon Battle Frontier facilities and own local leaders and there was no reason to delay this feature for a third cartridge game. And regardless, comparing the bonus features of HGSS to ORAS Johto wins hads down letting you use both past and new gen features, Pokewalk and many other things where ORAS best gift was a bunch of megas and 200 potions and the rest being an extended wild Pokemon spread and XY copypasta that may be useful with trading and such but sure not worthy the price and hype.
I also think it was difficult to introduce new battle facilities after two gens in a row already giving us 12 of those with some being similar to the previous region ones, although these few are considered mandatory, I'm sure Gen4 has covered all the possible gimmick clauses at time without attempting to create way to farfetched ones.
