Well technically it isn't ever over, but if you want action then... Here are some things.
1. Defeat the battle frontier
2. Capture latias and latios
3. Get rayquaza
4. Raise pokemon to lv. 100 and battle or transfer them to other games. (diamond/pearl or
black/white
5. Complete regional and national pokedex.
:d from: groyvlegoodbye125

6. Go to steven's house and you'll see that he let you get a beldum
7. Go to the desert underpass in the fossil house in fallarbor, and you'll find the other
fossil
8. Talk to the weather institute man and he'll tell you where you can find kyogre and
groudon (one at a time)
9. Go back to the trick house and take on the trick master's final challenge (if you
haven't taken on his other challenges, you have to take on them first)