Of course, the submission-dependent radar is very much vulnerable to trolling (anyone can say they just spotted a Mewtwo at the Empire State Building, for example), which the creators acknowledge in the app's help section. To combat this, they created an "intelligent" rating system that allows you to up-vote or down-vote Pokémon sightings based on how helpful they are. In other words, you can help remove bogus sightings by voting them down.
With any luck, you'll find and catch a Charizard -- or maybe even a Vaporeon -- in no time.
Until then, have fun encountering zillions of Rattatas, Pigeys, Zubats, Spearows, and other garbage Pokémon (and enjoy this updated version of the Pokémon rap):