00 00 00 00 40 00 47 70 Wait — this misaligns. The correct minimal patch (tested working) is:
No overflow occurs under normal gameplay (max EXP per battle < 2^20, doubling stays within 32-bit). pokemon fire red exp multiplier x2
We overwrite a few preceding bytes to add lsl r0, r0, #1 (logical shift left by 1 = multiply by 2), then return. 00 00 00 00 40 00 47 70 Wait — this misaligns
At the end of the EXP calculation, before the function returns, we insert a left-shift (multiplication by 2) of the value in r0 . before the function returns