11/10 They're good ghosts I'm meh about shedinja. With an emphasis on weather and fields, as well as enemies with diverse teams, I don't think it'll last long. Gengar is always nice and Mismagias has good coverage or sablye for support.
Destiny knot will pick 5 ivs between the two parents. the 6th is random, so you'll only need 5/6 ivs. replace pokemon with better ones to increase the odds of getting what you want.
Find the aqua gang member in Lapis Ward, he'll tell you he sold it at 7th street. In 7th street, there's a second vendor who will sell you the magikarp for some shards.