Ditto is a perfect Pokémon.
Just look at it. It’s a wiggly little blob so indistinct that you can’t even tell if it’s more like putty or like gelatin, with the most inscrutable, empty little smile. It’s present, but with virtually nothing to it, except for that this creature is utterly and blissfully vacant.
Which is exactly what Ditto should be. Full marks.
Ditto is such a weirdo as far as in-game usability. Its one gimmick – completely copying the opponent down to their stats – mostly makes it useful if you’re behind the game’s level curve, since grinding won’t do it much good once Transformed. It’s even worse in a few ways, since it requires a turn of setup, doesn’t copy Hit Point values (Ditto’s are pretty atrocious), and has a few other minor drawbacks. There are a few situations where Ditto’s gimmick is useful as a doubles partner, but to be frank, it’s mostly useful for its out-of-battle features rather than as a teammate.
Ditto’s extreme uniqueness makes it pretty popular; it’s been a monster-of-the-week feature in the anime at least three times, it’s a two-time invitee to Super Smash Bros., and it plays a memorable part in the Detective Pikachu movie. On top of that, it’s pretty common in merchandising, including an entire line of plush dolls of Ditto masquerading as other monsters (given away by their dopey dot-eyes and thin-line grin). Everybody loves a Ditto, apparently.
That signature gimmick informs every square inch of Ditto’s identity, including why most people keep them around: breeding. Since Ditto is based around transforming into other monsters, it can in turn reproduce with any other monster in the game – up to and including, bizarrely enough, non-gendered and inorganic monsters. The only ones it can’t reproduce with are other Ditto and one-off Legendary Pokémon, because the online trading economy has to have some rare commodities in it.
It also results in Ditto being the source of a ton of in-game glitches, especially in the first two generations of games. It triggers a famous glitch that spawns the otherwise-uncatchable Mew, can trick wild Pokémon into having stats that make it a guaranteed ultra-rare “shiny” Pokémon when migrated to newer games, and creates a few otherwise-impossible move-learning scenarios. Knowing what Ditto is and does, it’s a small miracle that it doesn’t cause the games to freak out even more than they already do.
That transform move also causes it to get up to trouble in certain side-games of the franchise, typically as the player encountering another monster that turns out to be a Ditto in disguise. A particularly amusing and recent example was the release of a certain mythical Pokémon in GO, where that new and mythical Pokémon was very common for a short time – but in the form of a horde of Ditto masquerading as said new monster. Those little pranksters.
One element of this that’s been dropped over the years, though, is Ditto’s coloration. Originally, it would appear as an entirely purple-colored (pink-colored?) version of the opponent on transformation, giving it the appearance of a bizarre alien blob that’s merely been pressed into the shape of the opponent rather than a literal reconstruction. I kind of like this very uncanny take on a duplication monster, but I have to admit that continuing to include it as the graphics continued to grow more complex would probably be more trouble than it would be worth.
There’s a bit of confusion about whether Ditto is supposed to retain that simple, dopey face when it transforms. It does in Pokémon Snap and in Detective Pikachu, though in those cases keeping the beady eyes makes for an easy visual shorthand in a more quick-moving action setting. The other case is with a certain Ditto in the TV series, where the “dot-eyes” expression is explicitly called out as an abnormal imperfection for a Ditto’s transformation. Again, this probably isn’t reflected in the games simply because adding in over 900 new “Ditto forms” would be a titch ridiculous just to cover for the Transform move, but it does give us that whole line of doofy-looking plush dolls, so I’m glad to have that interpretation out there.
Ditto isn’t the only monster to learn Transform, though. That and a few other hints (its habitat in Kanto, its coloration, and so on) lead fans to speculate that it was the refuse from a botched attempt to clone of the games’ very-first unobtainable, “mythic” Pokémon. If true, it’s a lovely little bit of environmental storytelling, but the official lore has never uttered a peep on the matter. Still, as far as conjecture goes, it makes for an excellent theory, and adds a certain uncomfortable wrinkle to the series’ world-building for those who want to dig for it.
Biologically, Ditto’s wild flexibility does have some drawbacks of its own. Ditto apparently has very little in the way of long-term memory, being unable to transform correctly into something that it has to recall the appearance of. This fits into the games a bit (you have to transform into a current opponent specifically), but also results in it being unable to do much on its own except turn into a simple rock as a self-defense mechanism. It also slips up and drops its disguise if made to laugh or lose its focus, which I choose to interpret as meaning that its Transform ability is tantamount to having a long staring contest with the opponent. I do kind of wish that the move “Tickle” actually disabled Transform in the games, but that’s such an edge case that it feels like it’d be more of an Easter Egg.
A few games also note that Transform isn’t necessarily perfect even with a subject directly in front of Ditto, with each individual having different strengths and weaknesses in its duplication. The only way I can really parse that is to think of it in terms of Elvis impersonators. Maybe some are more performance-oriented, duplicating movements and attacks flawlessly, while some are more aesthetics-focused and can replicate a Goldeen down to its detailed scale pattern?
Ditto has filled a particular niche since the day he was conceived, and seems to have only filled it better and better as time goes on thanks to how he interacts with the games’ out-of-battle mechanics. Plus, he’s just generally popular across the franchise and has been for years. This fella is a Must-Have that the series would be hard-pressed to be rid of mechanically or branding-wise.
Any and all appreciation for Ditto is welcome in the comments!