mega_evolve:
    push {r0-r7, lr}

    @ Allocate space on the stack
    @ We're going to generate a dynamic battle script in the RAM
    mov r4, sp
    sub r4, #0xFF
    @ldr r4, =(0x020375D8)

    @ Write the call byte
    mov r0, r4
    mov r1, #0x41
    strb r1, [r0]

    @ Next, write the pointer of the target script
   	adr r0, battle_script
    add r1, r4, #1
    bl unaligned_dword_write

    @ Write goto byte after the call command
    mov r1, #0x28
    strb r1, [r4, #5]

    @ Here we write the current battle script pointer. This makes it the target
    @ of the goto, so it will continue execution as normal after our little
    @ battle script...
    ldr r5, battle_script_insn_pointer
    ldr r0, [r5]
    add r1, r4, #6
    bl unaligned_dword_write

    @ Now we execute our script
    str r4, [r5]

    @ Change da species
    ldr r0, battle_participants
    ldr r1, battle_active
    ldrb r1, [r1]
    mov r2, #0x58
    mul r1, r2
    @add r0, r1
    mov r1, #3
    strh r1, [r0]

    pop {r0-r7, pc}