Turns you into the resourceful rat, without the synergy. This will behave exactly as in the vanilla game, including stopping the actual Resourceful Rat from taking your stuff you leave behind. The only differences is that your hand textures are also changed, and also you can toggle it off. If you are playing coop you can set one or both players to be rats. Note this is not a texture swap in the usual sense; it is an ingame costume override, (somewhat) as the actual synergy does it. Your portrait and minimap icon, and everything else like that, will continue to be that of your chosen character.

Installation:
Requires ETG Mod - download and install that if you have not.
Place downloaded file into your steam/steamapps/common/enter the gungeon/mod folder
Update or delete your mods.txt file

Use:
After entering the gungeon, open the ETGMod console and enter "Ratto".
Optionally, enter "Ratto 1" to swap only player 1's status, or "Ratto 2" to swap the coop partner's status.
Enter the command again to revoke rat status.
This will not persist thru saving and loading, so in that case just re-enter the command. Otherwise it will stay activated throughout your run.

Known issues:
Overriden by other model changes; re-entering the command once (or twice) should fix this if you want.
Flag designating rat status persists between runs, resulting in command doing apparently nothing. Just re-enter the command again.

Source code: 
https://pastebin.com/f2rxCYWX (prior version)