After you deafet the Pokemon league on Pokemon Diamond what can you do?

Answer 1

After you defeat the Pokemon league, you will start back to your room back home. You're mom has a message for you, and its from your rival. Your mom give you a ticket to a place once you have obtain the upgraded national pokedex, but first, you must complete the original pokedex. You've probaly have seen 149 out of 150 Pokemon total in your pokedex. If you don't, look for the missing Pokemon. Now, if you end up with 149 Pokemon, you need 1 more Pokemon to go. If you have Daimond, you need to see Palkia. For Pearl, you must see Dialga in order to complete your pokedex. Don't know how? The problem could be easily solved. Once you have 149 Pokemon, talk to the professor's assistant Lucas/Dawn. He'll/She'll tell you to talk to Cynthia's Grandmother. Once you reach Cynthia's grandmother's, she'll tell you a tale of Palkia(Daimond) or Dialga(Pearl). With that, you'll get your pokedex completed with 150 Pokemon total! Once you did that, head back to Sandgem town and talk to Professor Rowan. He'll give you a warm congratz. Then Professor Oak; the professor from the Kanto region, will have a surprising visit to the lab and will also be inpressed with your hard working effort. Professor Oak had known Professor Rowan very well and are also good friends. Anyways, Professor Oak will upgrade your pokedex to the National Pokedex. That means there's more Pokemon for you to discover, catch, and train than those 150 Pokemon you've seen or collected in your original pokedex. Now that your pokedex is upgraded, you can now use that ticket to head off to a new place you have never been before. That new place is filled with new Pokemon which can help you a lot with the National Pokedex. Also, there are 6 new legendary and rare Pokemon you can catch after you have defeated the Pokemon League. 3 Pokemon can be caught in the game, and the other 3 needs a special requirement in order for you to catch them. If you want to catch or see new Pokemon, you can migrate Pokemon into Pokemon diamond and pearl. I predict Migrate means to exchange. If you have any game boy games, (besides game boy color) you can migrate Pokemon in the game you have and have it in Pokemon Daimond and Pearl. To find those migrated Pokemon, head to Pal Park which is in route 221(or 211) and catch those migrated Pokemon which can be added to the National Pokedex. There's a lot of things you can do once you defeat the Pokemon league. So...you're welcome!