Honestly, if Tyson appears, I'll be overjoyed. What if this is the scenario?
- Alain is fighting Mega Swampert with MC-X, when suddenly there's a hint of green in the sky and a girl runs by in a hurry, but she notices the black Charizard.
- Alain finishes the fight and is intrigued by the ongoing's.
- Alain and Manon come into contact with Iris, who has chased Rayquaza down to Hoenn.
- Iris notes that she's never seen a Charizard that looked like that.
- Alain notes that she has a Gible, and sulks that she hasn't evolved it yet and apparently doesn't know anything about Mega Evolution.
- Iris is pissed and runs off, going back to chasing Rayquaza's trail.
- Alain figures that she might be the lead he needs to find Rayquaza, which he learned holds a key to Mega Evolution.
- He starts chasing Iris, but ends up facing both Tyson and Steven who were clashing with their Mega Metagross.
- Alain than fights Tyson's Mega Sceptile and wins, and loses to Steven's Mega Metagross.
- He tries to find Iris and he does eventually find her and Rayquaza. MC-X and Dragonite fight against Rayquaza, but as legends tend to do, it simply leaves the scene.
Not too difficult, and would be extremely fun to watch in my opinion.