Which games do I need to buy and play?

Hi there, I'm brand new here and I've got a total newbie's question for you all. I hope this is the right place to ask it.
I've got an old Gameboy Advance SP2 (I'm going to start saving up for a DS) and I'm new to the Pokemon games. I want to try to catch as many Pokemon as I can (without special events and that kind of stuff, obviously), so I'm here to ask how I can do that.

Which of the games available to the Gameboy Advance SP should I buy, and in what order should I play them?

I probably can't afford to buy all of the Pokemon games all the way back to Red, Blue, and Green, so what are the minimum games I would need to buy and play in order to catch all of the Pokemon I can?

And, once I play them all, can I transfer my Pokemon to the DS Pokemon games (Black and White?) when I finally buy my DS?

Thanks for you patience as I try to figure all this out.

Hmmm... This is really a difficult question and I think you won't like the answer I'll give you. :D

To catch every possible Pokémon in 3rd gen without events, you'll need one copy of Ruby, Sapphire, Fire Red, Leaf Green and Emerald each, which are all of the games released on the GBA.

Reason is that Ruby has some Pokémon that Sapphire doesn't, and both have Pokémon that Emerald doesn't. Moreover, to catch most of the Kanto and Johto Pokémon, either Fire Red or Leaf Green are needed, and Fire Red has some Pokémon Leaf Green doesn't, and vice-versa. Also, there are no Hoenn Pokémon in FRLG. On top of that, Emerald has a few Pokémon none of the other games have. It's really that complicated!

If you're short on cash, I suggest getting Emerald and Fire Red.

As for the second question, you'll need a DS with the GBA slot if you want to transfer Pokémon. Then you can transfer to a 4th gen game via Pal Park and, from those games, transfer again to 5th gen.

Cerberus87, thanks so much for your thorough response to my very basic question. It's very helpful and appreciated!

1. If I get all of the games you list, does it matter in which order I play them?
2. And, once I finish Fire Red (or whichever game I play first), how do I transfer the Pokemon I capture in it over to Leaf Green (or whichever game I play next) when I start playing that?
3. Am I correct in understanding that Ruby, Emerald, and Sapphire are almost exactly the same game, but with a few different exclusive Pokemon?
4. Am I correct in understanding that Emerald is a remake of Leaf Green and almost exactly the same game, but with a few different exclusive Pokemon?

Thanks again! It's all kind of confusing to a newbie!

Since you've already gotten a few replies, I'm gonna close this. I recommend simply asking quick questions in this thread in future.

Locked.