How do you get Bonsly in Pokemon Diamond?

Answer 1

In the Trophy Garden. Go to the Trophy Garden in Hearthome City. Go into the mansion, turn right and talk to the mayor and he will say he saw Bonsly, Igglybuff, Jiglypuff, Meowth, Eevee, Minun, Plusle, Castform and lots of other rare Pokemon (you must have National Pokedex). Each day, the mansion owner will change which rare Pokemon he has seen in his garden. It will be one of the Pokemon listed above (or a few others such as Porygon) and you must wait until he states a Bonsly was sighted in his garden. The Bonsly will then begin to appear in the patch of grass outside the mansion. Alternatively, you could trade for a Bonsly from a Pearl version or breed a Sudowoodo you have migrated from Pokemon Emerald.