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

Acreus
I was 読書 something on some website,(I don't remember it, I was half-asleep that night) it 発言しました in Pokemon Diamond, Pearl, and Platinum that getting Acreus was as easy as breeding Dialga, Palkia, または Giratina (depending on which game あなた 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 発言しました 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!