Ok so, I'm playing Pokémon Soul Silver, and I trained a Magikarp to be able to make him evolve into a Gyarados. Now, my Magikarp is lvl 19, and soon to be 20 (which is the level that it will evolve). But I also know that if I keep leveling up my Magikarp up to lvl 30, it will learn the attack "flail".
Now, my question is: is it worth it to make it level up to level 30 so that it will learn the attack Flail, or should I just make it evolve already?
Because, I don't know if it will have an impact if I decide to make my Magikarp evolve only at level 30. For instance, does the stats of the Gyarados will be bigger if I evolve it at 20 and make it level up to 30, or if it would have the same stats regardless of the time I made it evolve?
Anyway, I hope my question is clear! Thank you for taking time to read this and potentially helping me out :)