It is the fourth facility Platinum challenges, in Chapter 429. She battles two days without rest in order to reach Argenta.
In the Battle Hall, you choose your opponent's type and battle with your single favorite Pokemon species. It's one-on-one for single battles, and two-on-two for double battles.
The challenger first chooses the type of Pokemon that he or she wants to fight against. The Pokemon of the type start at "Rank 1", then progress up to "Rank 2" and so on after the challenger wins against them.
The ranks goes up to 10. Each of the 17 types have 10 ranks; the goals of the trainers who challenge this facility is to win all 17x10 battles. The numbers of consecutive wins are saved in the challengers' total record. Each challenger tries to see how far their Pokemon's winning streak can go. Frontier Brain Kate shows up on 170th Battle. Held items are allowed