So one day Elijah convinces Jer to perform in a contest with him as his partner. He had his doubts but after rehearsing a bit and picking out costumes it turned out to be a major success. And in the end Jer and Elijah had a good time and their bonds with their Pokemon strengthened, increasing the power of their Mega Evolution.

Jer and Elijah belong to me
Art belongs to a friend whom of which will remain ambiguous.
Lucario and Gardevoir belong to Pokemon/Game Freak

The Lucario (Dante) belongs to Jer while the Gardevoir (Serenity) belongs to Elijah.