I had created a Pokemon Go account using a school email account way back when the game came out and I didn't foresee that it would eventually be deleted. I am aware that you can swap emails if you use a real or dummy FaceBook account, but considering that I am currently unable to even log in, this isn't an option at this time. My problem--though honestly somewhat self-inflicted--is this: is there a way to get back into my account? I already contacted Niantic and am awaiting some form of a response to my request, but since it would seem their track record for responding isn't the greatest, I thought I'd pool my resources and see what I can do.
I know you have already contacted them but your best action would be to wait to hear back from Niantic support and see if they are able to restore the account data to a new G-Mail or Pokemon Go account.
Your best bet would be to find any receipts of any in game purchases you made, through PayPal, bank card purchases etc as they will have a transaction ID that they may be able to link with your account.
Without this they have no way to confirm you are the original owner of the deleted G-Mail account and will probably not restore said account.
im new at this but did you have your account synced to like a phone maybe as like a recovery number and how long has your account get been deleted for? if it hasn't been deleted for long go here maybe it might help https://support.google.com/accounts/answer/6236295?hl=en