>>48594572>that's when the entirety of Galar was watching and he wants everyone to know he's the one who "solved their energy crisis". This. Chairman Rose's entire thing was that he got his ass kicked in the league finals when he was young and spent his whole life over-compensating for it. He was a poor boy from a small coal mining town who came close to achieving greatness, but fell just short and was never able to move on. He did it on the day of the league specifically because he wanted to be the one who was celebrated by the huge crowd during the league finals, unlike last time. He doesn't give a shit about the energy nonsense, he just wants closure.
The reason he looks meaningfully down at his Pokeball before the match isn't because he's having second thoughts, it's because battling you is giving him flashbacks to the loss that's been haunting him all this time. At the start of the battle, you can tell he's obviously very hesitant to relive the memory, but by the end of it he's yelling out attacks like he's having fun. Reliving the battle that way allowed him to finally put things into perspective and remember he enjoyed the journey even if he didn't win, so he was finally able to let go of his demons.
Unfortunately, Rose's history with the league is only mentioned in optional text, so the piece of his backstory that makes the character come together is something a lot of people miss.