The Battle Hall is at the upper-left corner of the Battle Frontier. Here, you enter one Pokémon of your choosing for one-on-one battles. The objective is to keep your winning streak going as long as possible.
At the Battle Hall, you may take Single or Double Battle challenges alone. For the Single Battle challenge, you enter one Pokémon of at least Lv. 30. The Double Battle Challenge requires you to enter two of the same kind of Pokémon that are at least Lv. 30 each. Winning-streak records are kept for individual kinds of Pokémon. That makes it possible for any kind of Pokémon to aim for no. 1. When you enter the Hall, you will be asked to choose the type and rank of the Pokémon you want to battle. If you manage to win ten matches in a row, you will earn Battle Points (BP). If you want to interrupt your challenge, please save the game. If you don’t save, you will be disqualified from your challenge. Please be aware of that!
Each type is initially set at Rank 1. You will have to choose one of these types. Your next opponent's Pokemon will be of the type you selected. With each victory, the rank of that type will increase by 1, maxing out at 10. With each increase in rank, the level of your opponent's Pokemon is increased by two. Once 10 trainers from one type have been defeated, that type is completed and can no longer be chosen.
Opponents' levels are always lower than or equal to yours. When you start out, your opponents' Pokemon may be as many 30 levels lower than yours, and they gradually increase (even among different types) as you extend your winning streak. The Frontier Brain's Pokemon levels always match yours.
You do NOT have to finish off a type during a streak. The streak goes by number of battles (in this case, 10), so you can finish the Level 1s for ten different types if you want to. Note that to win the colored stamp in your Battle Recorder, you do have to max out all 17 types to Level 10, for a total of 170 battles.
The strategy is to make your moveset as diverse as possible. Given that you're limited to just one Pokemon, you can only have moves representing four different types. Still, do you what you can: there should never be two moves of the same type. Pick a Pokemon like Spiritomb, whose Ghost/Dark combo leaves no outright weakness. Be cautious when picking types that your Pokemon is strong against, as some of your opponents' high-rank Pokemon will have second types that are advantageous against your Pokemon (for example, if you have a fiery Chimchar, you might go up against a Water/Grass Ludicolo who knows Hydro Pump.) Plan accordingly so you don't fall into that trap.
Hall Matron ARGENTA
Battle Hall Frontier Brain
(Note: ??? denotes Pokémon and moves that are chosen at random.)