Nope. Nothing affects the shiny ratio other than pokeradar/consecutive fishing/masuada method/[unconfirmed-friend safari].
Edit: Just got my 29th shiny.
Are any of those for trade? [except dragalge and gyarados-got them]. And as for pokerader...so hard to pull off, and then they troll you with empty patches.
fishing is easy though.
You run Solar power charizard in addition to ninetails. Ninetails is your basic sun producer. charizard ohkos stuff with solar power till it runs out, then mega evolves to keep the sun going. And why can't you get weather ball on a carterage? just get an ivysaur from the safari zone and breed it.