I got a Lapras yesterday, weak one though.
If you are moving they glitch even more, sometimes due to GPS glitch. If your speed is more then 30kmh they will go off, as Niantic doesnt want people driving while playing.
Never short of magikarps... unless you dont do gym battles.
Still waiting for a shiny magikarp, but if get a weak one, what is the point of evolving it?