Do Pokemon grow or do they just hatch the same size that they will always be For example is a wailmer egg huge or is the wailmer small and grow with age or does it magically grow instantly?

Answer 1

Pokemon in the Pokemon Games (Emerald, Fire Red, Leaf Green, Ruby, Sapphire, Diamond, and Pearl) do not have eggs their size. For example, when an egg is hatched from a wailmer, the egg will be the same size as the others, but the Pokemon hatched will be the original size. In Pokemon Heart Gold, Soul Silver, Crystal, Platinum, and Gold, however, the Pokemon size eggs do have some variety, but only if traded to another game. If you're asking if it is noticeable in the game however, then the answer is no, the eggs will be the same (or look the same in the game) size and the Pokemon will grow to its size after hatching.