Q:

Forgot to run Sysprep before migrating a VM to a new Azure account

I've been tasked with migrating our VMs from our old Azure Account to our new one. 
I knew nothing about anything when I started the process a few days ago.  I decided the best thing to do was take it one step at a time.  So I reassigned our subscription, moved the storage blobs, disassociated the Os's with the old disks and deleted all the VM's.  I just created the new disks from the VHDs in the Blob. 
The last step was to create an image from the disk so I could make the new VM's. 
Turns out, I should have run Sysprep.  I didn't. 
What.  Do.  I. Do.  Questionmark. 

A:

You should just need to sysprep any machines you imaged with the un-sysprepped image.  Make sure to take an image of one of these to use for a new standard image (This will need to be done after you sysprep and before you boot the system back into the OS for the OOBE or automated configuration. 