RE: Magikarp?
1. IVs mean diddly-squat in Nuzlocke Runs, Solo Runs, or just plain In-Game Runs. Same with EVs.
2. Just use the switch out tactic (send out Magikarp and then switch something stronger in) to gain Experience. It depends where you are in the game and what other Pokemon you have (if any, hopefully you have at least something moderately strong...) but you'll gain levels sooner or later.
dmaster out.