BluekiKatana, have you tried any new tests lately?
All the tests I keep trying are proving to be consistant. From what I've seen, the everstone compatability looks to work like this:
Everstone Breeding Compatability in D/P
1.) 4th gen obtained + 4th gen obtained (everstone attached to female)
Nature will pass 50% of the time
2.) Pal park Pokemon + 4th gen Pokemon (everstone attached to female)
Nature will not pass 50% of the time
3.) Pal park Pokemon + Pal park Pokemon (everstone attached to female)
Nature will pass 50% of the time
One could argue that this makes Dittos from Pal Park useless (I thought it might too.) However, with the new Ditto trick you can get new egg moves on your offspring versions of your old Pokemon. Here is the Ditto trick for those who don't know it. It is highly recommended for breeding egg moves.
Breeding egg moves with Ditto
With this trick I recommend a Smeargle, and a Ditto is required.
1.) Get into a 2vs2 battle (south of the flower city is a good place).
2.) Make sure you're starting out with Ditto and Smeargle. Smeargle has to have all your desired egg moves.
3.) Transform into Smeargle, don't switch Smeargle out yet.
4.) Once Ditto is transformed into Smeargle, switch Smeargle into something that will knock out Ditto.
5.) Knock out Ditto, and voila you now have a Ditto with your Smeargle's set of moves and they will pass down to any Pokemon that can learn them.
One thing to remember in this process. Even if you're breeding the Ditto with a female, you still attach the everstone to the Ditto, because it gets priority on the everstone trick. I also don't know for sure whether this is a glitch or a genuine new addition to the breeding system. However, it works consistantly for me, so I say it
is not a glitch.