Fluggerson

Can someone help me? I started doing this today. Sometimes this works sometimes it doesn't. I made a Diancie, but put it in the wrong ball so I remade it and it didn't show up.. Am I only allowed to have one Pokémon hacked of each kind? I also tried to make an event mew but i failed to do so.. I made a greninja and i said it hatched at daycare helpers..