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.
Wailmer cannot be found in Pokemon Black. They are found in the old games.
Wailmer evolves into Wailord starting at level 40.
The Pokemon Wailmer evolves into Wailord at level 40 on Pokemon Black.
Wailmer evolves at Level 40.
Wailmer evolves at Level 40.
Wailmer evolves into Wailord at level 40.
A wailord
wailmer
wailmer evolves at level 40 on Pokemon sappphire.Hope I helped
My wailmer evolved earlier today at level 40.
Wailmer EDIT: I think Wailmer can only learn dive.
Wailmer is #320 in the national pokedex, and it is a Water type Pokemon.