you can migrate from saphire, or you can catch a ralts in the safari zone and evolve it
Pretty much any psychic Pokemon but I suggest Gardevior, Espeon, Alakazam, and Xatu. Movesets Gardevior Psychic Protect Shadow Ball Calm Mind Espeon Psychic Shadow Ball Trump Card Protect To Lazy to Do the rest check SMOGON
Lopunny, Gardevior, and Medicham (i think gardevior should get together with team raider's gallade)
Wally, the true rival of Pokemon ruby, sapphire and emerald.
The first Psychic you'll encounter has one.
you can't find a gardevior in the wild
Yes
There is no best Pokemon on Pokemon HeartGold.
there is no Pokemon Mansion in Heartgold.
Gardevior psychic on tentacruel thunderbolt on the rest except whiscash use Breloom
They are not in Pokemon HeartGold
yes. go to victory road and cross the bridge, you go to the right, use rock climb (down), then go to the left and there will be a trainer. he has a haunter, a gengar, then a gardevior. hope that helped
you have to get a ralts and level it up to 30. the first evolution is kirlia (at level 20)