#1 Do a Nuzlocke run
I've attempted a few Nuzlocke runs in the past, and they have all ended in bitter failure because Nuzlocke runs are the most hardcore and difficult way to play Pokemon. Nuzlocke runs were designed to make replaying Pokemon games more exciting and varied, alleviating any repetitiveness and lack of challenge garnered through a dozen retreaded adventures. There are a lot of self-imposed rules in a Nuzlocke run, some of them optional, but these four rules are considered necessary:
1. If a Pokemon faints, it is "dead" and cannot be used anymore.
2. If you run out of Pokemon, it's game over and you must restart.
3. You can only catch the first Pokemon you meet in each area with no second chances.
4. You can only use Pokemon you captured yourself, which excludes Pokemon given to you during the course of the story. Excluding your starter Pokemon, of course.
Yeah, Nuzlocke runs are tough. They're easily the most difficult way to play Pokemon; therefore, if you really want a challenging Pokemon experience, but don't want to wallow in misery after 25 hours of play time when your starter "dies," you should consider the five other points in this list before diving into the deep end.
You can read more the rules of a Nuzlocke run here. Good luck.