After you beat Giovanni you get a video of him saying "Now go fact the puzzle master" you will then get the key to puzzle city. After the credits roll you will get a code to unlock all the missing characters in vs mode.

1p stadium. Easy after you beat Giovanni you will get a picture with a bunch of Pokemon on it that says congratulation.

Normal. After you beat Burno you will get an elite medal. Then a picture of Ash holding a Pokeball, and surrounded by his friends and his mother appears.

Hard mode. After beating Gary a 2nd time you will see a short clip of Ash holding up a trophy and cheering. The credits will role and you will get a code to unlock very hard.

Very hard. After you beat Gary a 2nd time it will show Ash holding up a trophy. Except this time the Trophy is glowing. Ash will stop and look at his trophy and say what is inside by trophy. There is a bright light, and Ash finds himself standing in front of the true puzzle master. The puzzle master is none other then the worlds favorite homicidal super clone Mewtwo.

If you are defeated by Mewtwo you will get a short clip of him saying he doesn't have time for games and you will be sent back to beat Gary. If you beat Mewtwo you will get a clip of a light surrounding Ash and Pikachu. After that has subsided Ash finds him self by the pool and easy chair he was sitting in before the league began. He says it must have been a dream until he see's a puzzle master trophy sitting on a nearby table. A congratulations screen appears and then the credits role. After them you get a code for super hard mode.