If it is just Gmail, then most residential IPs are sufficient for that purpose. However, nowadays apart from the resources such as proxy, IP, etc, what is more important is the account creation method, because of Google being now more aware that Gmail, etc accounts are getting a lot more created by people using bots (scripts, softwares, etc), so they've beefed up their algorithms accordingly.
However as far as the IP aspect is concerned, for Gmail accounts creation, most residential IPs are good enough.