When they explain the machines power, one of the things it can do is grant eternal life. This almost happened to the Protagonists when you stop Lysandre from destroying the world.
So AZ and his Pokemon have eternal life. Simple right?
His height is probably a combination of the main character (you) being shorter than average, and him being taller than average. My bet is that if he weren't who he was he'd be a famous Basketball player.