So as you are guessing that google will know the screen size, mouse movements, key strokes speed by measuring the difference between keypress down and keypress up, you will need to randomize this and change them.
Also, make sure you change user-agent , browser plugins such as flash, adobe etc. Remember like you have heard, google can also see your macaddress so make sure to change that for each account.
@CrackFantasy also posted a link on things that Google can look for.
Keep in mind google can access your battery charge level as well so make sure to have different battery charging levels on for every account. Plus, google will also be able to access your webcam and take pictures so make sure you cover that so the pixel value of each picture is the same, else they will see the same person behind creating a lot of these accounts.
On top of that, make sure to also change your serial number for your mouse and keyboard as google has also figured a way to check on that. I've heard from people here that they can also check that.
Remember, don't forget to change the number of connected devices on your network as google can also scan your whole network and see what ips are connected to your network. They can make a hash and determined that the probability of all of these accounts having the same number of connected devices with the same ip on the network is probably a bot.
Last but not least, make sure you disable your gyroscope as google will most likely check for that, and your GPS on your phone if you are automating it.
So make sure you can fake all of those values and insert your own. Good luck my friend!
