There is no official "rarest Pokémon". It depends on what you mean by rare. In the main games, the best answer is usually a Mythical Pokémon, because many of them could only be had from special events. Others are rare in different ways: some are very hard to catch, some are hard to find in one gender, and a few forms show up just 1 time in 100.
Our own pick for the rarest comes at the end, marked as opinion.
Rare type 1: event-only Mythical Pokémon
Mythical is an official group of 23 Pokémon. For most of the series, you could only get them from event distributions, like a download, a code or a special in-store event. Bulbapedia says Mythicals were "traditionally" event-only, and that from Generation 6 several can be found in normal play too.
| Gen | Mythical Pokémon | Type |
|---|---|---|
| 1 | Mew | Psychic |
| 2 | Celebi | Psychic/Grass |
| 3 | Jirachi | Steel/Psychic |
| 3 | Deoxys | Psychic |
| 4 | Phione | Water |
| 4 | Manaphy | Water |
| 4 | Darkrai | Dark |
| 4 | Shaymin | Grass |
| 4 | Arceus | Normal |
| 5 | Victini | Psychic/Fire |
| 5 | Keldeo | Water/Fighting |
| 5 | Meloetta | Normal/Psychic |
| 5 | Genesect | Bug/Steel |
| 6 | Diancie | Rock/Fairy |
| 6 | Hoopa | Psychic/Ghost |
| 6 | Volcanion | Fire/Water |
| 7 | Magearna | Steel/Fairy |
| 7 | Marshadow | Fighting/Ghost |
| 7 | Zeraora | Electric |
| 7 | Meltan | Steel |
| 7 | Melmetal | Steel |
| 8 | Zarude | Dark/Grass |
| 9 | Pecharunt | Poison/Ghost |
Mythical and event-only are not quite the same thing. Bulbapedia notes that Zorua and Zoroark could only be got from events in Black and White, but they are not Mythical. For the difference between Legendary and Mythical, read Legendary vs Mythical.
Rare type 2: the hardest Pokémon to catch
Every species has a catch rate from 3 to 255. The higher the number, the easier the catch. A catch rate of 3 is the lowest in the games, and Bulbapedia notes it is used for most Legendary Pokémon.
In our data, 76 species have a catch rate of 3: 54 Legendary, 19 Mythical, and three ordinary Pokémon. Those three are the whole Beldum family: Beldum, Metang and Metagross. That makes Beldum as hard to catch as a Legendary, even though it is a small, common-looking Steel Pokémon.
These are the hardest Pokémon to catch that are not Legendary, Mythical, Ultra Beast or Paradox Pokémon:
| Pokémon | Catch rate (out of 255) | Group |
|---|---|---|
| Beldum | 3 | – |
| Metang | 3 | – |
| Metagross | 3 | pseudo-legendary (fan term) |
| Baxcalibur | 10 | pseudo-legendary (fan term) |
| Archaludon | 10 | – |
| Hydrapple | 10 | – |
| Volcarona | 15 | – |
| Snorlax | 25 | – |
| Scizor | 25 | – |
| Skarmory | 25 | – |
| Relicanth | 25 | – |
You can make any catch easier. Lower the Pokémon's HP and give it a status condition: from Generation 5 on, the catch formula gives a sleeping or frozen Pokémon a 2.5× bonus. Status conditions explained has the rest.
Rare type 3: forms with a 1-in-100 chance
Two evolutions added in Scarlet and Violet have a rare form that you can't choose:
- Dunsparce evolves into Dudunsparce when it levels up knowing Hyper Drill. Only 1 in 100 becomes the Three-Segment Form. The rest have two segments.
- Tandemaus evolves into Maushold at level 25. In our data, 1 in 100 becomes the Family of Three instead of the usual Family of Four.
Both are cosmetic, so they don't battle any differently. They are just rare.
Rare type 4: shiny Pokémon
Any Pokémon can be shiny, which means it has different colours. Since Generation 6 the normal chance is 1 in 4,096. A Shiny Charm raises it to about 1 in 1,366. Some special encounters can never be shiny at all. In Sword and Shield, for example, almost every in-game gift Pokémon is locked to its normal colours. Shiny Pokémon explained has the odds for every game.
Rare type 5: when most are male
Some Pokémon are rare in one gender. Many starters, Eevee and Riolu are 87.5% male and only 12.5% female in our data. Combee is 87.5% male too, and only female Combee evolve into Vespiquen. Salandit is 87.5% male, and only females evolve into Salazzle. Each of those needs you to find the rare one first.
What about Pokémon GO?
Pokémon GO is different. Which Pokémon appear changes with events, raids and the season, so a "rare" Pokémon can be easy to find next month. Lists of the rarest GO Pokémon go out of date quickly. Everything on this page is about the main series games.
Our pick (opinion)
This part is opinion, not an official ranking. We think the rarest Pokémon are the Mythicals from one-time events that never came back in normal play. If you missed the event, the only way to get one later is a trade from someone who didn't. Among ordinary Pokémon, our pick is a shiny Three-Segment Dudunsparce: a 1-in-100 form that also has to be shiny.
You can see every Mythical and Legendary on its own page in the Pokédex, and test your knowledge of the rare ones in the quizzes.