You guys are lucky, having seen the episode. You have seen it, right? I mean, you're all saying the Sawk VS. Throh battle is boring.
In all seriousness, a lot of you are complaining about bad writing only to suggest solutions that are worse.
Ash wins with Scraggy? The Pokémon that has received little training and been in a number of actual battles I can count on one hand against a group of powerful first-stage and evolved Pokémon with moves he's weak against?
Bianca winning everything? Yeah, really credible when all she did was barrel through the one rival even less credible than she is herself and then win a second match with a massive type advantage, purely because she brought a cannon to a gun fight? Seriously, Trip hasn't won a battle on-screen since BW010 and anyone who thought Georgia's Bisharp could beat the worst type combination she could possibly face was lying to themselves. With how devoid of any development Bianca is - no on-screen victories, still completely incompetent as we can see in the Smash previews - the only way the writers could do anything with her was give her the biggest muscle in the tournament and let her loose on a helpless joke rival and a horrifically imbalanced type matchup.
I don't think the outcome of Stephan VS. Masaomi is as obvious as people think. Luke was never given the kind of attention Masaomi is getting, so him becoming a new rival (hopefully to replace the pathetic mess that is Trip...) is more likely. We know little about him so far, so for example, what if he decides to head for the League because he's won the Donamite (at least) twice? That is one possible scenario. It's also a lot more believable if the 'threat' League rival is introduced earlier compared to coming out of nowhere like Tobias did; if Masaomi shows up at the Unova League, it strikes me a lot like if A.J. returned for the Kanto League so long ago.