It depends.
the girl and old guy are ghost i think you can talk to them
Its behind the bush near the one guy with the hat.
from the pokech guy
It is Lumineon a water type. There is a trainer that has one..He/she(don't remember if it was a guy or girl) can be seen on your way to the Pokemon league.
from the foreign guy
hes not in platinum:( try ruby
hs in the Pokemon league
veilstone city, in a house right above the Pokemon center
there is a guy under cycling road or maybe it is a wild pokemon
A guy walks into a bar OUCH:)
Talk to the guy in floroma meadows
This guy named Blake on route 216.