Lucas's (or Dawn's) sister tells you where to find Pokemon from other regions, such as beldum, mareep, caterpie, and more. You should speak to her every day to get a different Pokemon.
Speak to Dawn's/Lucas' little sister, she will tell you about 15 different rare pokemon.
talk to dawn's sister every day and she will tell you where a rare Pokemon is. P.S. she only tells you one Pokemon per day
Your rival's sister tells you about rare Pokemon appearances. Each day a rare Pokemon will swarm one route, if you go where she says, you'll find the Pokemon.
If you go to the TV in Dawn/Lucas' house or ask Dawn/Lucas' little sister she will tell you a rare Pokemon of the day. Or you can use your Pokeradar.
They're rare, so you just have to find one by chance.
its a swarm, you have to check dawns house everyday. talk to her sister and she will tell you where the daily swarm is.
snow point temple. two rare Pokemon
Not really that rare... in Pokemon Diamond you can find Sunkerns on Route 204
you need the international pokedex otherwise she don't let you find rare Pokemon
shiny Pokemon are rare you can find them almost any were but they are super rare
Tropius is not rare.
Look for them in the grass