Well, that would depend on who you are, anonymous. If you have enough room to care for a wailord, then there’s nothing in terms of ethics that should stop you from catching a wailord. Likewise, keeping in mind that tamed water-types float, even if you were a trainer on the road, you may find that it’s easier to care for and battle with a wailord than one would think. However, if you don’t have enough space to care for one or if you battle primarily indoors, then yes, I wouldn’t recommend catching one.
Unless, of course, you happen to be the protagonist in a very specific subgenre of comedy that may or may not be highly popular with those who enjoy certain types of dubiously legal side hobbies.