Poison and Steel are super effective against fairy, yet when I used poison and/or steel moves they did normal damage. I can understand mahwile, as it's steel type, so is immune to poison and steel moves do i think 1/2 damage; and Mr. Mime is part psycic so poison won't do much, but steel should be super effective against both Mr. Mime and Sylveon, and poison agains sylveon would be supper effective as well.

I don't think the coders had been able to add the weaknesses of Fairy-types or dual Fairy-types yet. It'll be a little while, but right now you could just attack the second type of the Fairy-typed pokemon. For Sylveon, just use sheer force and hope for the best.

Thanks for the tip. It was Sylveon I had trouble with, 'cause like you said, I just used foul play on Mr. Mime and v-create on mahwile. However, sheer force is an ability, not a move... I didn't know abilities were on this rp.