Where can i watch this tournament? Is this going to be streaming on Twitch?

While I can see that possibility and would be okay with it, I really don't think it will for various reasons.

1. Their last battle was interrupted, albeit by a completely different reason, but still I doubt they'd do that twice in a row for such a highly anticipated battle.

2. Team Flare has no reason to interrupt. They way Lysandre talks to Ash in the episode preview makes it seem like he wants to watch and see Ash-Greninja in action, probably to try recruiting Ash like he did Alain, and interrupting the battle would just piss both of them off.

3. There isn't enough time left before Sun & Moon for another 6v6 league match and it'd be a little redundant. There's no way they'd leave the Kalos League without a victor.

4. The episode title "Kalos League Victory" implies just that, that there will be someone victorious at the League.

I don't know about Twitch, but I believe there are people who stream the live TV broadcast on Youtube if you want to watch the episodes asap.

You're conveniently ignoring the fact that his current team is blessed with the presence of Gawdlucha. Seriously, this is all Ash has to do:

1. Roll out Gawdlucha's Pokeball
2. Get to a safe distance away. Go get a Sprite from a vending machine or something
3. Check back every 15 minutes to see if Gawdlucha is done
4. Wipe the blood off of those cheap ass tennis shoes he's been wearing the last 20 years
5. Ash Ketchum, your new champion

 Then I'm going to double down on what I said earier. If he can't win the league with THAT team, then what hope does he ever have?

That team is essentially OU sans Noivern (Anime Pikachu would be OU-level). Greninja is ubers, and Ash's Greninja is uber-uber, so it's balanced out by Noiven and Goodra.

And that's before we even get to Gawdlucha, the Enlightened Savior of the uneducated masses...

His Hawlucha was jobbed out to a Slaking (yes a Slaking which it has a type advantage against) in the first round of the semi-finals. This is after it got a crazy entrance while wearing a superman cape as well.

Cmon now, Hawlucha is great, but not quite on the same level as Charizard/Snorlax, and definitely not an effortless auto-win lol.

To be fair, Hawlucha was at a disadvantage against Sawyer's strategy as they explained, yet he still played a major role in Slaking's knockout so it's not like he was defeated without contributing.

Never thought I'd see the day where asking if Ash will win a Pokemon League became a legitimate question

I sure as hell hope so. The thought of this even happening made me watch XY again

It's gonna be a loooong wait until the Final Match vs. Alain!

With the new Sun & Moon info we got today it looks like Pokemon Leagues as we've known them for the past 20 years are coming to an end, so it only makes sense for Ash to win the last traditional League!