To get Pokemon Go on iPhone in Canada you need to have an Apple ID account that is from the USA and then login with it on your iPhone to switch to the USA App Store.
First make a new email address (might as well be gmail so you can also use for Pokemon GO login)
Next make a new Apple ID with the address somewhere(anywhere) in the USA and then put “none” as your payment type
Do this at https://appleid.apple.com/ca/#!&page=create
After creating Apple ID check your email and verify account
~NEXT on your iPhone
Go to settings on iPhone
Go to “Apps and iTunes store” about half way down
Click on where it says “Apple ID” and then select Sign Out (or just sign in if you were not signed in already)
Sign in with your newly created apple ID with american address.
It will switch you to american App Store
Go to Top Charts Free and you should see Pokemon GO right at the top.