Battle Tower Black Screen Glitch
The Battle Tower black screen glitch manifests a black screen that is retained when you enter the battle room in the Battle Tower in Pokémon Platinum. You can still hear beeps if you press the A or B buttons, but the screen remains black. The music also still plays; and you may think you need to restart your game, but you do not.
This glitch ends your current winning streak even though you didn't lose. When it occurs, you are teleported back to the lobby and the game initiates the same dialogue that happens when you reload the game. The screen remains black, but you can still progress through this dialogue by pressing A or B, the aforementioned beeps from the initial description. Once the dialogue is cleared, you can move around and open the menu. The screen will remain black until the graphics are refreshed in some way, such as when opening the party menu or leaving the tower.
This glitch is caused by hitting a frame perfect B input during the black screen transition. Do not press the B button at all during this transition to avoid the glitch.
The code responsible is likely leftover debug code, but we don't know for sure. It was remedied in HeartGold and SoulSilver, and doesn't exist in Diamond or Pearl.
Thanks to RETIRE for helping with the investigation.