4th Gen Yeah I'm fishing for something...

So around march I decided it was a good idea to buy one of those distribution cartridges.
I wondered if it actually work about a day ago and in the way of unlocking mystery gift in my for-some-reason unstarted pokemon pearl (gotta love gen 4) I've decided that I want to capture a very specific pokemon before battling the rival. A very oddly specific pokemon, and a very stupid one. Using the old rod, I'm aiming to capture a level 15 magikarp. Funny thing is, the level range in all the fishing spot is... well, it is 3-15. Man I want tackle on that thing...

Just capture something you can battle with to catch any level karp, use it to slowly grind up karp until it learns Tackle, release other Pokemon= you're ready to go.

Believe me, trying to do it any other way will be a drain on your life for no real reason.