Yeah. Ash will let someone else borrow his Pikachu and his Gible will be a Garchomp. Later, that other guy turns against Ash and makes his Pikachu do his bidding.
So Ash now has to fight his Pikechu with his Garchomp... "Garchomp! Don't use Earthquake!" *Garchomp looks at him, puzzled* "Use Cut!" Meanwhile, the other guy says: "Pikachu! Use your magical Thunderbolt!" "PIIIIIIKKKAAAAAAA!!!!!"
And Garchomp dies and Pikachu feels sorry for Ash for some reason and rejoins him. And Ash revives his Garchomp and everything is back to normal. --- "Definition: 'Love' is making a shot to the knees of a target 120 kilometers away using an Aratech sniper rifle with a tri-light scope." -HK-47