Really? Why buy a newer version of a game you liked? One that adds new features and gameplay? Why buy mario 3 when you got mario 1? Or go on to Super Mario world? let's review the "SAME DAMN THING!"
Timeline: Gen 1: Red, blue, and yellow,
Limit of 6 pokemon party. (Staple)
Storage for up to 240 pokemon.
150(+1) species of Pokémon, with many related to each other by way of evolution.
A complex battle system, including:
o Five stats, HP, Attack, Defense, Speed, and Special. Different Pokémon have different stats, even among the same species.
o 15 different elemental types, which each Pokémon species has inherent to itself.
o 165 unique moves, restricted to four per Pokémon, each with its own elemental type, accuracy, base power, and effects.
* The Pokémon League challenge, Aka the gym battles and elite 4 + champion. Aka the main storyline.
All this AND you could trade pokemon and battle your friends via gamelink.
Gen 2. Gold, Silver, And Crystal.
Added 100 new pokemon. Total 251. Some are New evolutions to old pokemon as well as all new ones.
86 new moves. total 251.
2 new types. Steel and dark. Both were ment to weaken the "unstoppable" psychic types, and makes fighting types more useful.
Pokemon Breeding. Adding the baby pokemon.
2 more storage boxes for a total of 280 stored pokemon.
7 new types of pokeballs.
Built in clock to keep track of time and days for events.
hold Items added, for auto boosts, heals, and other effects.
Pokerus (pokemon Virus) which affects pokemon stats.
And a number of smaller Changes.
Gen 3. Ruby, Sapphire, Emerald, And remakes of red and blue, Redfire and Leafgreen.
135 new pokemon. 386 total. With brand new type combinations.
103 new moves. 354 total.
Added Abilities. An extra effect each pokemon has. 77 different abilities available.
Total storage of pokemon increased to 420.
The introduction of Pokémon Contests, where Pokémon show off their style in one of five Contest categories Aka, a whole another game inside the game.
Weather plays a larger factor.
Double battles, where both sides use two Pokémon at a time, introduced.
International linking is made possible.
Pokemon Natures were added to further make each pokemon unique.
Gen 4. Diamond, pearl, and platium. And remakes of gold and silver. Heartgold and SoulSilver.
107 new pokemon. Total 493. Lots of new evolution and Pre-evolutions for older pokemon.
113 new moves. total 467.
47 new abilites and removal of 1. for a total of 123. Many older pokemon have 2 possible abilities now.
Total 540 pokemon storage.
4 new pokeballs.
Moves are now marked as physical or special separately from type. improving game balance.
Trading/battling Via Wifi (this is not as good as it seemed at first.)
Pokemon contest are tweaked and improved.
Pokethons are added in HeartGold And SoulSilver.
That's not even ALL The changes. Just the big ones.
Point. Pokemon is a deep and complex as any RPG.
Now monster rancher, THATS the same game over and over again.