>>47533861I think that only applies for actual egg moves. If it's something the Pokemon can learn later on down the road from level up they can get the move much earlier. I recall something like happening to a playthrough of Pearl I did a long time ago.
>>47533831Try breeding one Horsea with any other mon (Make sure the Horsea isn't going to inherit any egg moves from the Father). Make sure the female Kingdra's moveset is mostly level up moves. IIRC the child should still inherit those moves. I could be remembering things wrong though.