So I installed ZSH and Oh my ZSH, rebooted and now whenever I attempt to login under any user it flashes and takes me straight back to the login prompt. I don't have a DM...
Send halp, I can't run commands to try to fix this myself...
If you have another PC install a VM with the current version of Linux you're using and install ZSH and try to trackdown where all the files are put. Than connect the drive of your PC to your other PC and find all the files you need to remove to get rid of ZSH.
I can boot from a live USB and fix it that way. I'm not sure how to remove software cleanly from Arch though.
You should be able to boot into recovery mode. OR, you just force the init to load /bin/zsh or /bin/bash or whatever is accessible on the system.
You can boot up the live Arch, and fix the zsh config file. Then try arch-chrooting in.
That's my plan
The ISO is on the laptop so I'm DLing it now
Well I suggested that because I don't exaclty now where ZSH is installed on Arch. But, I guess you're on the right way anyway to solve your problem. Good luck!