The Alolan region breathed fresh air into the series, ditched Pokémon gyms in favour of Trials, added new regional variants, a new enemy trainer faction, and a fantastic story.
4. Pokémon X and Y
Not only did this duo push the the series into 3D, the games elevated the battle sequences to new heights, introduced Pokémon Aime and laid the groundwork for the next generation.
3. Pokémon Ruby and Sapphire
The first games published truly in colour, the titles also introduced 2v2 battles for the first time, Pokémon natures could affect their stats, and weather conditions could be changed during battle.
2. Pokémon Red and Blue
The originals, but not quite the best, these games did a lot to cement the series long-term. Kanto and the classic 151 Pokémon still hold all the charm and fame too, and still headline all the merch to this day.
1. Pokémon Gold and Silver
Taking everything the original games did and making it better, these were the game that introduced day / night cycles, time-specific challenges, and even endgame content that added a whole new challenge.