'M' is a version of the Missingno glitch found in Pokemon Red and Blue. When doing the Missingno glitch on R/B and you come across a Pokemon named just 'M', Do not catch it. It -WILL- mess up your game (I've done it before, I lost my entire blue game because of it XP). Missingno is perfectly fine to catch, but 'M' is not.
http://bulbapedia.bulbagarden.net/wiki/Missigno
Google Pokemon diamon glitches sorry im not much help
you can find great glitches on IGN.com
there is no actual glitches like Pokemon yellow but there are certain cool hidden things throughout the game
All of the pokemon games have glitches in. Although you will notice that the older the games get the higher the amount of glitches there will be.
yes
Yes.
Yes.
none
Making a copy of a Pokemon by hacking or glitches.
Any glitches the game had have been sorted by updates of the game.
Yes.
only as glitches