once connected with super cell id all your gp progress gets transferred to supercell cloud..you cannot login from Google play games again
To avoid continuous login with email and OTP...just check ✔ on remember while login..this will save your login credentials..
If you switch to another Google play account the credentials are lost hence I suggest you to create supercell id for all your villages and switching to different account will be easier and faster
credits:KILLERCHEESE
Don't try again and again just wait 24 hour it will be open.
Last alert.
You can use whatever email address you like, but it must be different to any you have already created a Supercell ID for (i.e. you need one email address for each Supercell ID, and you can only have one clash account per Supercell ID). It does not have to be the same email address you used to connect the account to Google play originally.
Thanks TerMinus Prime for the sig pic
Use any id you want it does not matter as the progress will get transferred to that email account..but don't add up 2nd account to first 1 as it'll create error code saying that email already exists with different village
Try different account any you wish except the 1 which is already been used...hope this helps
credits:KILLERCHEESE