Why doesn't my Wailmer hatch with Aqua Ring?
Solution 1:
This might be because your version doesn't have this egg move. With the new games in each generation (first Platinum, then HG/SS), new egg moves are added, but these will only work if you do the breeding in that cartridge.
According to a quick search, Aqua Ring is only an egg move for Wailmer in HeartGold/SoulSilver. So, if you're doing this breeding experiment in Diamond/Pearl/Platinum, then it will not be passed on.