Coming back after leaving during Generation II

Generation II added Steel, Dark, breeding and a clock

Gold and Silver went on sale in Japan on 21 November 1999, and Crystal followed in December 2000. The games added 100 species for 251 in total and put Kanto after the credits as a second region. Dark and Steel brought the chart to 17 types, and Ghost finally hit Psychic for 2 times damage. Special split into Special Attack and Special Defense. The Route 34 Day Care introduced eggs, gender and egg moves, and shiny Pokémon appeared at 1 in 8,192. A real-time clock set day and night and weekday events, and friendship drove evolutions such as Golbat to Crobat. Crystal added the first selectable female player and the first move tutor.

Three rule changes since 2002 decide how a team is built

Ruby and Sapphire (2002) replaced DVs and stat experience with IVs from 0 to 31, effort values capped at 510, and 25 natures, and gave every species an ability. Diamond and Pearl (2006) gave each damaging move its own physical or special category, so Crunch and Shadow Ball stopped following their type. X and Y (2013) added Fairy, took away Steel's resistance to Ghost and Dark, and cut critical hits to 1.5 times damage. Breeding changed shape over the same years: the Destiny Knot passes five IVs from Generation VI, and Scarlet and Violet replaced the Day Care with eggs in a picnic basket. Each step has its own what-changed page.

HeartGold and SoulSilver are the last Johto games

HeartGold and SoulSilver remade Gold and Silver in 2009 on the Nintendo DS. They keep both regions, the clock and the weekday events, and add Generation IV rules, the lead Pokémon following the player, and the Pokéwalker pedometer in the box. They play on a DS, DSi or 3DS, and are sold today only as used cartridges. No Johto game has been released for Nintendo Switch. On current hardware, Scarlet and Violet carry the parts of Generation II that lasted: a day and night cycle, breeding, held items and a further area after the main story, here Kitakami and Blueberry Academy through the two-part expansion. Choose HeartGold or SoulSilver for Johto itself and Scarlet or Violet for the modern ruleset.

Gold, Silver and Crystal saves depend on one coin battery

The Game Boy Color cartridges keep both the save and the clock alive with one internal battery. When it runs flat the clock stops first and the save follows, and a battery swap clears the save unless it is copied off beforehand with a cartridge reader. A working cartridge still trades with Red, Blue and Yellow through the Time Capsule and a link cable, and Pokémon Stadium 2 on the Nintendo 64 reads it through the Transfer Pak. The Japanese Crystal used the Mobile System GB phone adapter for online trading; that service closed on 14 December 2002. The 3DS Virtual Console versions of Gold, Silver and Crystal could send Pokémon to Bank through Poké Transporter, and from Bank to HOME on the Premium plan, until Bank closes on 25 February 2027.

Limit. A stopped clock in Gold, Silver or Crystal means the battery is nearly flat; back up the save before anyone opens the cartridge.

Spend the first week on one region before you plan transfers

Day one: decide between a used HeartGold or SoulSilver cartridge and a current Switch game such as Scarlet or Violet; the which-game page lays out the options. Day two to four: play through the first three gyms or story stops and keep a note of moves that behave oddly. The Generation III and IV what-changed pages account for most of them. Day five: test each Game Boy Color cartridge. If the clock has stopped, the battery is close to gone, so back up any save you care about first. Day six: if you have the 3DS Virtual Console versions, read the HOME transfer checklist before you send anything to Bank. Day seven: draft a team with the first-team guide.