I have tried to breed these 2 Pokemon and the Day-Care told me 'The two prefer to play with other Pokemon than each other' which means they got 0% chance to breed... How is that? And how can I make it through?
You can breed Milotic with Corsola to have it learn Mirror Coat and breed it with any Pokemon from the Poliwag family to learn it Hypnosis. You cannot learn it both sadly.
They aren't in the same Egg Group, so they can't breed.
See here for more info on Egg Groups. http://pokemondb.net/mechanics/breeding
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