Use this infographic to see what Pokemon can hatch from different distance eggs!
Need extra Charmander Candy to evolve that Charizard? Pop a 2KM egg into the incubator and cross your fingers.
If you want to try and hatch a rare Pokemon such as Magmar, Mr. Mime or Onix then you need to incubate a 10KM Egg
Note that all region locked Pokemon can be hatched from an egg no matter which continent you live on.