>Red, Green
Pokemon established, made by hard work, soul, heart and passion.
>Blue
GF felt that RG wasn't complete and lacking, made an improved version.
=> Realized that they can make more money by selling a slightly altered game and market it as "better"
>Yellow
Special edition to commemorate the anime
>Gold, Silver
Sequel to RGBY, still made by heart, soul, and passion
>Crystal
Again, GF experimented whether third versions could sell well or not. Turns out it can
>Ruby, Sapphire
Franchise established. Time to experiment with features that would make the consumer happy.
Thus, double battles, abilities, reworked EV and IVs are put in.
>Fire Red, Leaf Green
=> "Fucking remaking the same game with updated graphics earned us millions, we are going to milk this thing so bad"
>Emerald
It sold pretty good
=>GF now knows that selling slightly altered things are profitable if they just market it as something bigger and better despite the changes are not significant enough to warrant a $40 game.
>Diamond, Pearl
A repeat of the last generation. Slight improvements in graphic and battle system with the new physical / special split
>Platinum
=>Same thing
>HGSS
=>Yeah
>Black, White
Experimented on new battle system the triple and rotation battles, experimented on introducing only new Pokemon in the new region outside of Japan
It fucking still sells like hotcake
>Black 2, White 2
=> This is the point GameFreak realizes that selling third version as paired improved versions brings in MORE MONEY

XY, ORAS, SM, USUM, and now SW•SH are the product of our negligence. We let GameFreak did this cause we consumed their games blindly instead of carefully choosing what to buy.
Let the normalfags buy the first paired versions, while we should wait for the third versions, where the region is fully unlocked.