it takes time but its by the day care center
At night on route 35 in the grass to the right on the 2nd square on the top.
You can find a Ditto on routes 34 and 45.
There is no way to get a golden Ditto in Pokemon HeartGold because it doesn't exist in the video games only a regular Ditto exists as well as a blue Ditto exists and a blue Ditto is known as a Shiny Pokemon.
You Can find it At Route 34/35/47 (if you are in Jhoto)
You need to mate the Pokemon with a Ditto.
Anywhere you can find a ditto, like below goldenrod (in heartgold), just keep looking till you find one. That is the only legit way I know, unless you get it in a trade.
You can find them in the wild on Routes 34, 35 and 47 in Johto as well as in the Cerulean Cave in Kanto.You can get a Ditto on Routes 34, 35, and 47. They can also be found in the Safari Zone and in Cerulean Cave on Pokemon HeartGold.
venusaur!?
You make them breed with Ditto.
breed a manaphy and a ditto
you find a Pokemon named ditto put him with daycare give him a mate it can be a boy or a girl some Pokemon cant love ditto eg. dialga legendary cant ditto neather can 2 heatrans male and female and togipea cant either
you cannot breed ditto with ditto.
evey Pokemon has an egg except legendarys and ditto