See In Order Route (Kanto)

 Kanto Dex / National Pokedex Order Section 1

=== Start ===

The first question in terms of rules here, is when does a pokemon count as seen? In this context, I will counting a pokemon as seen once you first reach a Pokemon Center after seeing the pokemon.

As such, starting with Bulbasaur, saving and quiting the game does not help. This would allow you to get all the 3 starters according to the save data of 3 games, but choosing Bulbasaur or Charmander is then required, the rival will take Charmander or Squirtle respectively, and then you have 2 SEEN for Kanto.

Total: 2 / 9

However, it is not possible to gain levels on the starter without first seeing wild pokemon to grind against. Therefore, the next part requires skipping straight to Oaks Parcel, returning to Oak, and heading through Route 1 again, never getting a wild encounter. Soft resetting the probability of this is required.

=== Brock ===

Once you can buy Poke Balls, you will able to catch the next pokemon - Caterpie. #10. Encountering a wild Caterpie will require soft resetting in case of finding other wilds.

Total: 3 / 10

Once Caterpie is obtained, it must be grinded to Butterfree, whilst only encountering wild Caterpie and Metapod. You are unable to fight the only mandatory trainer fight in the forest until you have Butterfree in the Dex.

The optimal way to get Caterpie > Butterfree is to play Leaf Green. Leaf Green has a higher grass spawn for Metapod than Fire Red does, though Caterpie/Metapod have the same rate. Red and Blue do improve these odds, but there is a better strategy.

Bug Catcher Charlie in FRLG has a team of 3 - Metapod, Caterpie and Metapod. It is consistent to fight the first two mons, faint to the third, and then soft resetting for wild encounters is not required. The trainers in r/B all start with Weedle, so this option is not available.

At Level 7, Caterpie will evolve into Metapod, and at Level 10, into Butterfree.

Total: 5 / 12

After Butterfree is obtained, you must repeat the same for Weedle. You will now be able to exit Viridian Forest to the north, as you can fight and defeat the Weedle, but to avoid the risks of running into wild Pikachu, the trainer path is the recommended path.

Total: 8 / 15

After this, you must then find your first Pidgey, and grind it all the way to Pidgeot under the same conditions, but to Level 36 rather than Level 10. There is still no soft-reset consistent method, as such, the trainer may continue to be the most consistent.

Total: 11 / 18

At least after Pidgeot, the grind for Rattata and then Raticate is only Level 20. Similarly, Spearow to Fearow is also Level 20.

After this, catching Pikachu in the Forest is possible.

Total: 16 / 25


Sandshrew is available in this section, as the Jr Trainer's pokemon in the gym, however, he uses Diglett in RB before Sandshrew is sent out, and uses Geodude in FRLG before.

And then, you must catch Nidoran F, evolve to Nidorina, but since the Moon Stone cannot be obtained, repeat for Nidoran M and Nidorino.

Total: 20 / 33

LGP may appear to allow obtaining Oddish and Gloom in this section, but is prevented by the rival using #133 Eevee, which also means Yellow is unable to progress at this time.

In Red/Blue, but not FRLG, the Jr Trainer in the gym uses a Diglett, followed by a Sandshrew. The Diglett is the next obtainable pokemon.

Total: 21 / 50

After this, FRLG can obtain Mankey, and grind up to Primeape at Level 28.

Total: 23 / 58

Bellsprout suffers the same fate as Oddish, available in Lets Go Eevee, technically even worse since the player is the one with the Eevee which cannot be registered.

After this however, the main Brock obstacle wall is required to progress. Brock sends out a Geodude and an Onix, jumping from #57 to #95 from one fight.

Total: 25 / 95

=== Misty ===

The next required fights use pokemon that are before Onix in the pokedex. The next required fight where this does not apply is the Super Nerd in Mt. Moon. This fight adds Voltorb #100 and then Koffing #109.

Total: 27 / 109

Misty is the next obvious roadblock, especially since we are already far into the pokedex order by this point. Trading Cut into the game could lead to improvements, but we cannot do so without encountering pokemon not available in this game at this time.

Chansey would be available in Lets Go, but is still locked until Eevee is optimal. The swimmer in the Cerulean Gym has a Horsea, the Cooltrainer has a Goldeen, and Misty has a Staryu and then a Starmie.

Total: 31 / 121

=== Remaining Sections ===

By the time you can defeat Misty, the trainers blocking you from using Cut do not use any pokemon later in the pokedex than your current position. As such, it is possible to capture an Abra and trade it for Mr Mime, registering it in the Pokedex.

Total: 32 / 122

Scyther is a Game Corner prize, allowing this to be added before the Safari Zone. Jynx is available by in-game trade for Poliwhirl, but Poliwag is not available with the Old Rod. Pinsir is also a Game Corner prize.

Total: 34 / 127

Magikarp can be obtained via the Old Rod however, which can be grinded into Gyarados. After this, it is possible to go through Silph Co, defeating the rival in order to obtain Lapras.

Total: 37 / 131

However, the literal roadblock, Snorlax, is required to be seen to progress to Fuschia City. But before this, it is possible to have Eevee, and, by use of multiple games, all 3 of the Kanto Eevolutions since you could get all three even in different save files. This does mean LG and Yellow are now free of jail, but by this time, they do not have any useful additions to the order. Porygon can now be purchased in the Game Corner, but the player cannot bypass Snorlax for any fossil checks before it's position in the pokedex.

Total: 42 / 137

With Snorlax obtained, it will be possible to get the 3 legendary birds before Dratini. Dratini must be seen in the Safari Zone, but since there is no remaining benefits, grinding Dratini is not required, since Lance will send out Dragonair and Dragonite. Wrapping up, Mewtwo is the final encounter.

Grand Total: 50 / 150 (33%)