Challenges you've probably heard of!
The classic; Nuzlocke
When a pokemon faints, it 'dies. Only catch the first pokemon you see each route, and all your 'mons need nicknames so you get attached.
Solo Run
Leave your pokeballs and dreams at home with mom, all you have to conquer the world is your starter!
Soul-link
You and your friend each play on your own, with nuzlocke rules. Player's pokemon caught in the same area are connected, if one dies or isn't caught the other one has to go too.
Ironman - One life, no turning back.
If your team gets wiped, delete the save and try again. That's it.