Still works for 1.2.4. OP can update first post to reflect so.
Addresses change throughout the day it seems. You can save your list and load it back up a few times before you have to search the new addresses again. Once you've found the first slot address and you can change the value of that address to 0, you should be able to see the VERY FIRST MONSTER in your list. THEN change it to a safe number (like one of your 1* silver monsters at the BOTTOM of the list). If your monster list max is 80, count backwards to the monster you want to clone (or let's say it's in slot 80) and then subtract one from that slot (in this case my last monster is in slot 80/80 the number I'm going to use is 79 to put into the address). So the 79th monster's ID NUMBER is actually 78.
After you find the FIRST SLOT'S ADDRESS (in the power up circle) fill the rest of the slots with trash monsters and THEN open GG and hit the 4th tab and search for the first slot's address in the bar (e.g. 774918B0 or something) and hit the GOTO button. The first line should read the address that you searched on the left (774929B0) and the value attached to the address on the right (0x000049 or something). The very next line will look like it has another address on the right side. Scroll down slowly and you'll see something that looked like that second line and the value ABOVE it will be the one to save (m2). Scroll down some more and you'll see a similar looking address (they all look like they start with 7) and the value ABOVE it will be the one to save. Same for 4th slot (m4). 5th slot is actually hardest to find because it doesn't have that indicating address value that starts with 7. It just ends with a bunch of 0x000000's. (don't quote me on how many zeroes cause I'm basing it off memory right now.)
I use this method to level up one 3* and make it into a 4* by cloning A DIFFERENT 3*, but best use comes out of feeding 1 devilmon to get 5 skill ups or 1 angelmon max level awakened and feed it like I'm feeding 5 instead.
Cheers.