I've had an idea sitting at the bottom of my documents folder for about a year now.
While digging for fossils, orbs, and shards in the Sinnoh underground, a wall collapses and a meteor is found by a crew of trainers. A metallurgist in Veilstone would later say that the metal is nearly indestructible and all pokemon are afraid of it because it can harm easily them regardless of type or ability. This metal can be used to create cages that can't be broken out of, more masterballs, and be armor for weapons like mechs and tanks. Once the news gets a hold of it, factions are formed among villains and heroes alike in order to either find all the metal and find a way to destroy it (throw it into the sun), use it as a means for a villainous return (Team Flare, Team Galactic, Maybe Rocket), or get rich off of it (everyone else).
I honestly don't know when I came up with this.
"Everyone creates the thing they dread. Men of peace create engines of war. Invaders create Avengers. People create... smaller people? Er... children! I lost the word there. Children. Designed to supplant them. To help them end."
But this is the traditional royal Canterlot voice! It is tradition to speak, using the Royal "we", and to use THIS MUCH VOLUME WHEN ADDRESSING OUR SUBJECTS!!