To get these pokémon, you have to get a male and a female from each. Azurill>Marrill can be found on route 117. Pichu>Pikachu can be found in the safari zone, Igglybuff>Jigglypuff can be found on route 115. Give a Marrill the sea incense from Mt. Pyre, the Pikachu the magnet from the Trick Master and the Jigglypuff the Silk Scarf from Dewford (the house right next to the boat) and leave them at the day care. After a While you get an egg, let it hatch and you've got them!