Dex mode 0x0B (map corruption): https://forums.glitchcity.info/index.php?topic=8318.0
Arbitrary code execution Dex modes: https://glitchcity.info/wiki/DexDex (pointers A000-FDFF)
*0x56: Pressing A on mode selection screen (from Select) multiple times may corrupt graphics on screen each time until a Glitch Dimension.
*0x73 seems to play Machoke's cry, however for some reason it doesn't allow for Coin Case glitch, possibly the lack of inc sp at the cry data.
*0xD8 brings up a corrupted dex listing screen and corrupts character 4 of your name with the 0x46 character. Not sure if this can vary. Has some use if you want to get boosted experience from your Pokémon.
*0xFE brings up the search screen instead of the listing which I feel is aesthetically nice. If you press Select you can press A to change the colour of the screen every time. Really fun.
*0x73: Does not cause arbitrary code so is safer than Gold/Silver's Dex mode 0x0B. If you press Select to bring up the mode selection screen and exit out with B you can corrupt certain maps including the train station. By saving and resetting you can get to Saffron City with two badges, but haven't found a way to get to the Pokémon League with this. May change dex mode to 0xE6 so you might have to change it back through the expanded Balls pocket after every use.
Arbitrary code execution Dex modes: https://glitchcity.info/wiki/DexDex ; (pointers A000-FDFF)