For those who are debating on the Battle Frontier, it is to be remembered that the HSGS remakes were thought up before Platinum, yes, but were not fully worked on until afterwards. This being said, that means features for the games could have been going in and out until the game satisfied the game designers of the remake. Seeing as Platinum was released first it is highly probable that this game came with the Frontier first, and to keep compatability with all the game's frontier they just kept the same data and moved it over into HG/SS. Regardless of whether the frontier was thought up for whichever game first, it has been kept the same no less. Yes, the feature could have been changed, but Game Freak has their reasons. Some like the idea of it, some don't, but keep in mind it isn't a mandatory feature of the game, it's 100% optional unless needbe.