You forgot Ditto, who is a failed attempt at cloning Mew.
Klink is a little more complicated.
Klink spontaneously came into existence “about 100 years ago” which roughly corresponds with the industrial revolution, since Pokemon is set in a parallel present. It’s also said in the anime that Trubbish spontaneously comes to life in garbage pits.
Okay so … the way a lot of media franchises work is that they have sort of a series bible that explains the finer points of everything, and it’s boring to just dump the series bible right out in the dialog so they’ll allude to a singular concept from different angles so that those concepts give you a glimpse of the whole idea.
Pokemon has been doing that for a while, and finally drove it home in Gen 5.
There’s this concept in Pokemon that Pokemon spontaneously come into existence as a result of the existence of another thing. This concept is never explained clearly and outright, but it’s hinted to at several points. The origin story of Voltorb and Klink are good examples, but so are Pokemon like Mr Mime and Vanillite.
Pokemon come into existence to reflect memes from the collective human consciousness. Real birds exist and humans understand that so new Pokemon come into existence that are based on real birds. You may also conclude that the animals that most Pokemon are “based” on could’ve been driven to extinction by their Pokemon counterparts, which is in no way supported in the games or comics or anime, but would be a reasonable conclusion.
Okay but wait there’s more!
Legendary Pokemon only exist because their legend exists. It’s like a chicken/egg problem. The lore of a legendary Pokemon makes it real. Arceus only created the universe because the people of Sinnoh believed it to be true, and it retroactively became true.
There’s this optional story thing in Heart Gold / Soul Silver where Cynthia talks about the connection between Johto’s Unown and Sinnoh’s Arcues legends, and how the two might be related. We then see a swarm of Unown bringing a new Arcues into existence - one totally different from the Arceus featured in the previous game.
Remember in the anime movie when Unown had the power to make dreams a reality? Pokemon exist as a result of human dreams and language and Unown are the manifestation of that concept.
That’s how Pokemon work.
My entire life makes sense.