It would probably come out later as an update. Even if they said that the project began on 2012, I wouldn't be surprise that the development/coding/whatever of the game, didn't began till a bit of time before the big reveal, so it wouldn't be surprising that Nintendo rush them to get the game out by November, so they had to leave some things out to add them later via updates, including the Battle Frontier.
Well that or there are some requierements to do in the game, and it gets build as you do it, something like defeat the E4, a certain number of times or something, though I doubt a Delta Emerald, specially now that we got the Delta Episode thing.
COMG guide to points: 1 point = Raging. 2 points = Beasting. 3 points = Tearing it up. 4 points = Berzerk. 7 points = Rampage. 12 points = Burst. 15 points = god mode. 20+ points = DIVIDING BY ZERO!!! 40+ points = Youkai (originally Pokemon).
-1 = Negabeasting. -5= NegaRampage. -10 = NegaBurst
