This Pokemon is Phione. Go to where you had to go to see Suicune's monument. Phione should be around there.
The newest Pokemon ranger game is Pokemon ranger: Guardian Signs.
It is in the Sky Fortress.
you don't catch it
on the route where you chase the Pokemon pinchers to their sub hideout
go east from tilt village
glameow
sentret
blastoise
Abomasnow
Togepi
Crobat
It is Lugia.
porygon2
latias is in Pokemon ranger signs.
Lugia
fall city is unt in Pokemon ranger guardian signs
Pokémon Ranger: Guardian Signs (Part One) and Pokémon Ranger: Guardian Signs (Part Two) or SS022 and SS023