Think we've got some sort of terminology misunderstanding here, since EV stands for Effort Value(s) for me..
Sorry, ment IV. Should I focus on speed, attack or HP?
/doesn't want to chain breed something that worthless
Thanks, and one last question, since I'm changing my single pokemon, does that count as a new challenge or just as an other attemt, since I only have the first badge?
Oh... Didn't realize ya started the challenge. Well, since I'm the one who talked ya into it, it'd be rude of me to make you get your first badge all over again, so no, you can just swap Pokemon and continue it as is. It's not like you've had the Dratini for very long anyways.
I'm only gonna warn people 'bout failing a Nuzlocke if their choice for the single combination is legitimately hopeless. I'll give advice if asked for, but I ain't gonna give anyone a list of excellent Pokemon to choose from. :P