@Hiroy:
I been wondering. Is it better to catch a Gyrados at Level 5 or so? It terms of status gain compared to when catching one at a higher level I mean
Well for starters, you can't catch Gyrados' that low, they remain Magikarps until level 20.
As for stat gains, not really. You earn IVs and such based on how much you fight and where you fight. So something you raised from scratch at level 50 WILL be stronger than something of the same species caught wild at level 50, but experience will eventually balance it out.
Unless you're being super anal and world class competition about it, and you plan to spend hours and hours in one area fighting a specific enemy type to get a specific gain, in which case your considering natures and ivs and bred moves into them and other such things… which is more effort than its worth for casual play.
Mostly just raising a critter will be all you need to worry about.
In the case of Magikarp specifically, catch it as close to level 20 as you can, those are a pain to level up due to their non existant attack ability.