Every pokemon movie has trailer has scenes in it that never makes it into the movie. They're the source of misassumptions and false rumors. Though I wonder why the clip is sufacing now, nearly 7 years after the movie originally released.
Some scenes from different movie trailers:
2nd movie:
Zapdos and Moltres collide on each other causing a beam of fire and lightning fired straight down to the Shamouti shrine. The shockwave blows away a lot of Pokémon. Pikachu being on of them. Ash jumps of a cliff yelling "Pikachu!" As Misty burst in tears and wants to go after him, Tracey stops her saying "Misty don't!".
The frozen sea where TR stands on suddenly breaches and Lugia arrise from it (as a silhouet with blue glowing eyes).
3rd movie:
The camera is inside a dark cave and is looking at the opening of the cave. Outside it is raining and a thunder lights up the cave. In that brief moment, Mewtwo's silhouet is seen.
4th movie
Bishir tries to squash Ash and Sammy with his mech.
5th movie:
Rion and Zanna stand in the museum sudden a giant Kabutops skeleton arise behind them and some pink lightning transforms the skeleton into a living Pokémon.
6th movie:
Butler summons some kind of lightning. Salamence flamethrower fits Flygon. Ash, Pikachu and Max gets knocked of Flygon's back. Diane reaches out to them.
7th movie:
The Battle Tower is burning in flames while Ash and Max stands on top of it. Deoxys fires a some kind of energy ball at them and makes a direct hit. Ash kneels down with an injured Pikachu in his arms. Suddenly the smokes clears up and Deoxys appears. Pikachu falls of the Battle Tower while Ash is yelling out for Pikachu.