Can heatran breed with Ditto

No, actually I tried that and it didn't work even though Heatran has a gender. You can't breed any legendary poke'mon except for Manaphy which gives you a Phione.

you can use action replay

Ya I tried you cant breed heatran with ditto, or at least not a male heatran.

No,even if it has gender it can't breed.Well,Heatran and Cresselia are legendaries alright,but not Rotom.Rotom CAN breed,if you have a Ditto. Here is proof they are legendaries/not:

Rotom:http://bulbapedia.bulbagarden.net/wiki/Rotom_(Pok%C3%A9mon)

Cresselia:http://bulbapedia.bulbagarden.net/wiki/Cresselia

Heatran:http://bulbapedia.bulbagarden.net/wiki/Heatran.LatiOS and Latias can't breed too.