Then the army would declare war and kill them all.
Seriously, it won't be like in the cartoon. I mean, how would the police feel if a gyarados rampaged through a city? And remember, pokemon aren't invincible.
well Pokemon isn't stupid/obnoctious like Billy and mandy >.> but if Pokemon existed in this world we would probably be dead :S I mean they could turn on us and since they can shoot lightning, and poison us we wouldn't be a challenge lol.