So there is a mega mechanic in the game. w
When you use a Sync Move with a Pokémon that can Mega Evolve, after the move is used they retain their Mega form with boosted stats and upgraded moves.

Examples:
When Karen's Houndoom mega evolves, Bite becomes Dark Pulse
Lucario's Vacuum Wave becomes Power-Up-Punch (which is what Korrina's Sync Move is based on)

Also characters like Noland and Agatha get Mega Pinsir and Mega Gengar, so we can expect more Megas down the road.