I do know about the glitches in Gen.4 games. And no, I have never obtained these Pokemon through a glitch, because these glitches are actually quite dangerous with hazardous consequences!
The Surf Glitch
The Surf Glitch, or void glitch, is a Gen.4 glitch known for capturing the legendary Pokemon Darkrai and Shaymin. This glitch can be compared with the Tweaking Glitch. The Surf Glitch ONLY appears in the Japanese versions of Pokemon Diamond and Pokemon Pearl.
Due to an error in Aaron's room of the Pokemon League, a player can Surf through by facing the door and selecting Surf from the party screen. The player can now step into the void around the indoor area and pretty much walk into any other area.
By counting your steps using the Poketch, you can travel to Newmoon Island and the FLower Pradaise without needing the event-exclusive items such as Member Card and Oak's Letter. You can catch Darkrai and Shaymin at these locations and then Fly back to an accessible area.
Performing this glitch comes however, with danger and must be performed with caution! Because the player can enter a void area, these areas aren't programmed properly since you would normally be unable to access these areas. You risk getting stuck forever if you do. Saving outside these boundaries or in the Mystery Zone may cause data corruption including the loss of your save file.
There isn't any way your game is free from these risks, because with the Surf glitch and Tweaking glitch, you are at high risk of corrupting your game/ loosing saved data!
The Tweaking Glitch
Tweaking is a glitch in Diamond, Pearl, Platinum, HeartGold and SoulSilver that causes your game to load the graphics of an area.
CAUTION: Tweaking has not been performed succesfully in ANY non-Generation 4 game!
In Gen.4, all maps are broken up into square sections of 32 tiles by 32 tiles. At any given time, only 4 sections are loaded and visible making the sections in the direction of the player loaded into the memory and the sections behind the player are unloaded. Through this, the overworld appears seamless.
But, using the bicycle in the fourth gear, can cause the player to move too fast for the game to load these areas properly, loading and unloading multiple sections nearly simultaneously. By doing this you can trigger a race condition bug causing sections to load improperly. The effects can vary from game freezes, invisible walls, a black area, a white area or even a different section to load in the wrong place.
So, depending on the layout of a section, it's possible to tweak in such a way to load a walkable black area into a section that does not normally contain a walkable surface. This allows you to a number of shortcuts, such as skipping to Moon Island, skipping Tohjo Falls and so on. In sections containing buildings a player can enter, by tweaking to create a black area, it's possible to enter buildings blocked by NPC's by standing in the tile where the NPC's would have been loaded (locked hotel in Gen.4). Such shortcuts are possible in all Gen.4 games.
Like you, I love glitches too but I wouldn't recommend trying this, EVER :3
imo, it's already too late for you once you started performing these glitches ;)
