I really want to play Pokémon Go but I am a completionist. If I start playing now, what Pokémon won't I be able to catch?
edit: the list is getting a bit out of date. I do not have time right now to update it, but a lot of previous legendaries are obtainable via the 7-day research reward, or coming back into legendary raids. Also, trading is now a thing, making it a lot easier to get eveerything you missed. The only ones you currently misseed are via special quests. These quests should have been picked up (but not completed) in a certain time period. Rewards for those were:
- Meltan (but obtainable via a Mystery Box)
There were multiple limited time Pokemon, mostly legendaries. It is currently not known if they will return (all of them or a select group). These Pokemon were:
- (Shiny) Lugia
- (Shiny) Ho-oh
Currently there is another legendary active, Latios/Latias (and shiny Ho-Oh), so be sure to catch that one while it is still possible. Also Mewtwo is available through Ex-raids at this moment in time.
The legendary birds (Articuno, Moltres, Zapdos) were twice catchable. First a week per bird, then about another month where all 3 birds were available at the same time. Now Zapdos is available by finishing a research quest on 7 individual days. Moltres was already available. Articuno will be available in June.
Another 'issue' might be the special hats for the Pikachu family. At specific moments in time they were catchable/hatchable with a different hat.
One other thing that might be annoying is that there are regional Pokemon. For example, Farfetch'd is limited to Asia only. However, there has been an event where it was catchable for 48 hours worldwide. You can still catch Farfetch'd in Asia, but not so soon in your hometown (if not located in Asia) though.
The regions of Seviper and Zangoose are switched right now. Catch the one that should not be in your location!
Posting an updated answer since the old one is outdated.
Kanto Pokedex. All Pokemon are obtainable.
Jotho Pokedex. All Pokemon are obtainable.
Hoenn Pokedex. Kecleon is still the only unobtainable Pokemon.
Sinnoh Pokedex. The unobtainable Pokemon are:
- Rotom (all forms except for Wash are unobtainable)
- Phione and Manaphy
- Shaymin (both forms)
- Arceus (all forms)
Unova Pokedex. The unobtainable Pokemon are:
Zorua + Zoroark
Larvesta + Volcarona
Kyurem-Black and Kyurem-White (base form is available)
Keldeo (both forms)
Meloetta Pirouette form (Aria/base form is available)
Genesect Chill Drive form (base, Burn, Douse and Shock Drive forms are available)
Zen mode Darmanitan (Unovan and Galarian, base modes are available)
Kalos Pokedex. The Pokemon listed below and their evolutions are unavailable:
Zygarde (all forms)
Alolan Pokedex. The following Pokemon and their evolutions are available, in addition to all Alolan forms:
Rockruff (Available Lyncanroc forms are Midday and Midnight, but not Dusk)
Galarian Pokedex. The following Pokemon and their evolutions are available, in addition to all Galarian forms except Articuno, Zapdos, Moltres, and Corsola:
Zacian (base form only)
Zamazenta (base form only)
Zarude (base/non-Dada form only)
Hisuian Pokedex. No Pokemon are obtainable. However, Hisuian Voltorb and Electrode are available.
Unknown Pokedex. All Pokemon are obtainable (Meltan and Melmetal)
Many of the obtainable Pokemon can't currently be caught, for example most legendaries. If starting now, you'll need to trade with a player to obtain these Pokemon. Unfortunately Mythical Pokemon other than Meltan and Melmetal can't be traded. Hence Mythicals that aren't currently available cannot be obtained until they became available again. Mew, Celebi, Jirachi, and Victini are available through special quests without a time limit; hence they can still be obtained.
The unobtainable Pokemon that have previously been released are:
- Deoxys (all formes)
- Zarude (must have started Special Research quest from 1st to 10th October 2021)