Kanto pokemon were more prevalent in Johto's encounter rates in Gold & Silver. Many pokemon like Marill and Yanma had a 1% encounter rate. Some pokemon like Slugma, Houndour, and Larvitar were only found in Kanto.

In Gen 3, Game Freak made people buy a Gamecube and two games to get Ho-Oh and Lugia. In FRLG, you could only get Johto pokemon in the post-game. 21 regular Johto pokemon could only be found within those two games or the player had to wait until Emerald. Pokemon that include Houndour, Smeargle, and Ampharos.

With HGSS, it had the same crummy encounter rates from GS. Larvitar was still only found in Kanto. These games were more like another Kanto celebration.

X & Y treated Johto better then any other pokemon game. 63/100 were found within the game and icons like Heracross, Houndoom, Ampharos, Tyranitar, and Scizor got mega evolutions.