>1996 - [9.0] Pokémon Red/Green (Red/Blue/Yellow)
The concept of forming a party of monsters that join you is not new to JRPGs, but Pokémon implemented it in a smooth, never-seen before way. It's a solid game, solid JRPG and one of the best games of the GB.

>1999 - [10.0] Pokémon Gold/Silver (Crystal)
Expanded even more an already revolutionary game. Being a sequel story to the original, included locations of the previous game as well as trading compatibility with it's predecessor. Introduced new concepts like genders, types and numerous new battle mechanics. Tried to be one of the most immersive GB games of it's time with it's day-night cycle, as well as daily events - perfect for a handheld game. Crystal went even further with the female protagonist, Pokémon animations and online battling.

>2002 - [7.0] Pokémon Ruby/Sapphire (Emerald)
Disappointing game that scrapped many of the game mechanics built until then. Featured a smaller map, barely any time events and no compatibility with previous games. Introduced new Pokémon, but only a bit more than half of the total were obtainable. Introduced new battle mechanics, but created a great gap between casual and competitive play with the introduction of Hidden and Effort Values. It's still a fun core Pokémon game with the mechanics that everybody loves, though.

>2004 - [7.0] Pokémon Fire Red/Leaf Green
Overall lazy remake of the original, with few new content and reusing many assets of the previous game.

>2006 - [8.0] Pokémon Diamond/Pearl (Platinum)
Pokémon's first step into 3D went smooth, with good use of the new hardware. It's a pleasant game that follows the formula stablished in Ruby/Sapphire. Went on par with the expectations.

>2009 - [8.5] Pokémon Heart Gold/Soul Silver
Also made good use of the new hardware, updating a great game from the GB to the DS. The only core game to ever have a general following Pokémon mechanic.