Ok so i found a glitch that could be big. now if im not mistaken shaymin and darkria are aloud because of the glitch to get them. now this glitch allows moves like belly drum and aqua jet to be on an azumarril with NO CHEATING DEVICE.
1.there is a glitch that allows ditto to keep the pokemon it transforms into moves. you simply transform and have the pokemon kill you.
2. once i discovered this i immediatly got my smeargle to learn belly drum and aqua jet. i did the procces described in the first step in a double battle.
3. now ditto has both moves i bred ditto with a female marril and sure enough the hatched marril had both moves.
the reason why this is important is because in theory it could change the whole illegal movesets issue.
should this be considored a legitimate set. and im sorry if this is in the wrong section but it didnt seem to go anywhere else
This glitch (and the one you mentioned about Darkrai and Shaymin) were only found in early versions of the Japanese Diamond\Pearl. They are not found in any other language version or any Japanese DP produced after that. No, they are not considered legitimate movesets.