Where do you find rare Pokemon in Pokemon Diamond?
If you want rotom a ghost electric type which is very rare you go to the haunted mansion in eterna forest at 12o clock (you can just change the time on your DS) then go up onto the landing and into the door in the middle of it, then go to the room with the TV and press a when you get up to it. It will say something is inside the TV want to thump it you say yes and rotom will come out of the tv i would always use a quick ball to catch him hope that helps Heatran is found in Stark Mountain after the quest with Buck (lv 70)
Giratina is found in the Turnback cave after you have passed three pillars (lv 70) Regigigas is found at the bottom of snowpoint temple (requires Regirock, Regiice, Registeel, lv 70) Cresselia is roaming Sinnoh after encountering her at Fullmoon island (lv 50, talk to the sick kid in the house in Canalave) You can get cresselia by getting a genar or haunter that can u mean look.
At the old chateau, which you can visit after beating gardenia, if you interact with the TV (in the upstairs room) at midnight you can battle a level 15 rotom. You can breed rotom with ditto.
If u want to get a eevee go to hearthome go to the house next to the poke center and u will find Bebe(u must complete the sinnoh dex)Talk to her and she'll give u a eevee.there a other one in the master garden.Use the poke radar and go to the sparkles and u will find eevee.(u might not find eevee if u try the first time)To get more eevees go get a ditto.You can find one in the patch of grass in route 218. Use the pokeradar and go to the sparkles.Then go to solaceon town and go to the daycare.Put ditto and eevee together and you will have tons of eevee eggs!