I saw your post in the shiny pokemon thread, if you want better odds of getting a shiny mareep then you should get a static lead pokemon. (such as voltorb/pikachu/ or even another mareep) having a pokemon with static at the front of your party increases your odds of running into electric types so you'd be more likely to get a mareep. I'm not sure if you knew that or not but I figured I'd let you know just in case :3