Hoenn, Ash lost to the eventual winner of the conference league, but it's really up in the air since Tyson was struggling harder than Ash before the full battles phase of the tournament. It's arguable that Ash was the second strongest trainer there though.
Following up with this and other posts that mention the Hoenn League since it's still fresh in my mind, Ash struggled--good struggles compared to Johto and Kanto, but they were still struggles. I don't see how having close calls meant being good enough to get to the finals and win the League. I may not be a competitor so I don't know the exact strengths of each Pokémon, but I believe Glalie and Corphish, maybe even Torkoal were the weaker members of Ash's team when he entered the League, like there was more he could've done with them. Which is funny because Glalie and Corphish WERE the ones who got him up to the battle with Katie, but it was
still a fight to get there--and he continued to struggle. I'm surprised he
didn't lose against Katie, she knew what she was doing, and this was him at his worst the entire League. (Using Thunderbolt on a Dugtrio? Really?) It was pure
writer's influence luck Corphish was wacky when confused and threw her off long enough for Ash to make a comeback.
Meanwhile, in response to the bolded, Tyson showed the most promise the entire time, and though Ash gave him a good fight (they were about on equal terms, anyway), he didn't appear to have struggled once with his strategies, even during the (quick) glimpses of the battles with seen him in before his battle with Ash. That's why he won (although I wish we could've seen the tail-end of the final fight). Maybe if Ash went with Pikachu in Grovyle's place against Metagross, he could've had a chance since the strategy he used with Grovyle was the same as with Pikachu?