Great idea! And heres some more stuff on it.
When you approach the Champion, He says you must be really strong to make it this far and compliments you. He says his name is Josiah. As you examine him closer, you see a team oblivion badge on him. And the scar that every team oblivion leader is said to have. You tell him, and then four trainers come from the ground through elevators. Josiah exclaims how him and his masters will rule the world once again, just as they had in the past. So you battle him, and his executives. When you defeat him, a portal comes in the air behind him and he escapes through there. The professor tells you to follow, and so leads to the last major event (Which I will not yet reveal otherwise it spoils it)