If I'm not wrong, neither Canada or Mexico have aircraft carrier ships. They have ships with choppers, but not planes. Also, Mexico doesn't have submarines and while Canada does have them, they are diesel.
Those factors, coupled by the (and I don't want to be rude) superior naval experience of other European navies like UK's Royal Navy, would mean that with the US taking care of Russia, the navies of the european countries would have a clerarly superior advantage over the Canada/Mexico ones.
America is known to already supply Mexico with guns.
Hence, we give the Mexicans more guns and send them over as the main infantry men to Europe. You guys would be fucked. That is 118,000,000 hard working Mexicans.