The reason I say 0x027FFFA8 is more common because in most codes (even in the codejunkies codes), 0x027FFFA8 is more commonly used than 0x02FFFFA8. I honestly have never seen 0x02FFFFA8 being used, but in the end they all are doing the same thing. I normally use 0x027FFFA8 when using X or Y as an activator, but then again, I try to work around using NDS buttons for activators since the game(s) tend to use them for something else. Anyway, thanks for sharing that with me.
questioner, for the broken L button, you could actually trick the game into thinking that the current button you're pressing is actually the "L" button (with a debugger of course). If you just want it changed to something else you could use this:
GBA Button Address: 0x04000130
NDS Button Address: 0x027FFFA8/0x02FFFFA8
GBA Buttons:
0x0001, 0xFFFE @A Button
0x0002, 0xFFFD @B Button
0x0004, 0xFFFB @Select Button
0x0008, 0xFFF7 @Start Button
0x0010, 0xFFEF @Right Button
0x0020, 0xFFDF @Left Button
0x0040, 0xFFBF @Up Button
0x0080, 0xFF7F @Down Button
0x0100, 0xFEFF @R Button
0x0200, 0xFDFF @L Button
NDS Buttons:
0x0400, 0xFBFF @X Button
0x0800, 0xF7FF @Y Button
Select one of those and change all the ones I labeled as "L button," "R button," and "Select Button" in the code.
Edit 1: Looking into another game with a debugger (non-Pokémon game) also sets the NDS buttons to 0x027FFFA8 in r3, while the GBA buttons are in r1. Although showing which registers they're in is relatively irrelevant, what stands out in the picture is 0x027FFFA8.
Edit 2: Next to the first image happens to be Pokémon Platinum using that very same address. Over on Kodewerx, they have this, "All commercial DS games share two universal activators, one used for handling all the buttons the GBA has and another used for the DS-unique buttons. The address for the GBA buttons is at 0x04000130, and the address for DS-specific button address is located at 0x027FFFA8." Anyway, I love learning new things so I really do appreciate your clarification as it was something I wasn't used to seeing.