Do NOT waste your time on these, they DO NOT work!

Acreus
I was pagbaba something on some website,(I don't remember it, I was half-asleep that night) it sinabi in Pokemon Diamond, Pearl, and Platinum that getting Acreus was as easy as breeding Dialga, Palkia, or Giratina (depending on which game you are playing) with a Ditto.
1: Ditto plus any pokemon always is that pokemon- with the exception of Manaphy.
2: Legendaries can't be bred.

Shaymin

The same site sinabi that Carnivine plus Staraptor is Shaymin.
1: Legendaries can't be obtained this way.
2: I got a Tropius this way.

Remember don't waste your time with these!