Meh...
I became a berry enthusiast after I caught Rayquaza... tried making bushes with the most berries they could possibly hold. Some of the higher-level berries I could only get two of, but I've gotten 16 oran berries on one bush before. :D After I got some really good pokeblocks made, I did the contest thing.
Then I caught my first shiny. I decided to be a shiny hunter after that.
After hunting for about 50 hours of game time and not finding another shiny, I gave up on that and went to catching all the pokemon. Never did that, tho. Lost interest, lol.
Battle tower is freakin' hard! I hardly ever win. >_< My pokemon suck eggs, for some reason. Probably because I rarely ev train... oooh! There you go! Build up some EV powerhouses! There's always a chance you could get into a battle with a real person someday. 9_9
*edit*
Btw, you could also try to steal all the items wild pokemon carry. I actually ran into another one of my shinies doing that, and I got a ton of poison barbs, twistedspoons, dragon scales, etc. They're good items for trading to your friends too. :)