Pokémon

Fundamental Mechanics:
 * HP / Attack / Defense / Special Attack / Special Defense / Speed
 * Level / Experience
 * IVs / EVs
 * Friendship (Happiness)

Persistent World Mechanics:
 * https://bulbapedia.bulbagarden.net/wiki/Time
 * https://bulbapedia.bulbagarden.net/wiki/Days_of_the_week
 * https://bulbapedia.bulbagarden.net/wiki/Weather
 * https://bulbapedia.bulbagarden.net/wiki/Season_(mechanic)
 * https://bulbapedia.bulbagarden.net/wiki/Berry_tree
 * https://bulbapedia.bulbagarden.net/wiki/Bug-Catching_Contest
 * https://bulbapedia.bulbagarden.net/wiki/Kurt (Apricorns > Pokeballs)

Gen 1

 * Bicycle
 * A History of Pokémon through the Internal List - HelixChamber

Gen 2

 * https://bulbapedia.bulbagarden.net/wiki/Pok%C3%A9gear
 * https://bulbapedia.bulbagarden.net/wiki/Mom_(Johto)
 * https://bulbapedia.bulbagarden.net/wiki/Radio_in_the_Pok%C3%A9mon_world
 * Roaming Pokemon
 * Shiny Pokemon
 * Pokemon Stadium 1 Colour Variations
 * Gender
 * Red
 * Special Attack/Defence Split


 * Japanese Exclusive:
 * https://bulbapedia.bulbagarden.net/wiki/Pok%C3%A9mon_Communication_Center
 * https://bulbapedia.bulbagarden.net/wiki/Mobile_Stadium
 * https://bulbapedia.bulbagarden.net/wiki/GS_Ball

Gen 3

 * Abilities
 * Secret Base

Gen 4

 * Physical/Special split

Spin-Offs

 * Pokemon Snap
 * Pokemon Pinball