who is he
I actually really like XanderO's explanation of that a few posts up. I hadn't realized Aerial Ace's Japanese name was Swallow Return; knowing that, it makes a lot more sense as to why Pokemon like Diglett can learn it!
The Japanese names really do help in understanding why some Pokemon learn certain moves...or, reversely, it helps understand more about the Pokemon that is using it. For instance, I couldn't really determine what, besides a humanoid, Jynx could be based off of, but after reading that her signature attack "Lovely Kiss" is "Demon Kiss" in Japanese, the correlation between her and a succubus made a lot more sense.
Another example of that would be Hoppip learning Splash. Some people might think that it doesn't make sense, but its Japanese name is actually "Hop."