How to get a male Pichu in pokemon heart gold?

Ok, I'm familiar with pokemon. There are a few things when you are breeding pokemon. When you breed a male and female of a species you have a 50/50 chance on which gender the egg will be. When breeding with a ditto, the gender of the pokemon with the ditto decides what the gender will be. For example, a female pikachu and a ditto can only make more female pichus, that's a rule of the game. But if you mate a male pikachu and a ditto you have a chance of getting either or. I don't understand why they put it like that. Also, an egg's gender is set as soon as its made. So it doesn't matter how many times you hatch it.