There is no possible way you can get Contrary Snivy.......Gen 2 and Gen 5 starters are the only ones who didn't get their HAs yets. If you have a contrary snivy its a hacked one.
Why not make it even harder, and make a randomnizer and start with that pokemon. like Bulbasaur is 1, Squirtle is 2, Charmander is 3, etc. and whatever number the randomnizer chooses, use that pokemon it's actually really fun.