I'd say due to the backlash from the last series and the fact the League this time isn't a long-established League with a prestigious history, he will actually end up winning this one. They could also use it as Ash's in to gain an invitation/sponsorship for the Galar League in the next series. The fact it's Ash/Gladion in the final and the winner fights MR (who Gladion has had no interaction or seeming interest in, while Ash fought against him twice, with him once and vowed to have another battle with him when they next met) also seems to heavily indicate it'll be Ash that wins (can't see Gladion sticking around after the League, he'll want to restart his search for Daddy and I can't see Ash accepting the MR match as a consolation prize if Gladion beats him, but fucks off to go look for Daddy either).