Need Quick Answers to Pokemon DS Games!

So, my son hasn't played any. Should he play Black or White prior to Black 2 or White 2? If I get him Black would he then later need to play through Black 2 or can he switch to White 2? Does it matter? Should I skip the first iterations and just get one of the sequels? Seems there could be more life if he has to play through the originals than one of the sequels? Damn, can one play through all four? What's the difference between the Black/White series and the earlier ones? Better gameplay? Those damn EX pokemon?

Placing an order soon, so I need to know this. Thanks!

Whenever there's a Pokemon question like this, the answer to pick the newest version. I'd go with Black/White 2. It has more Pokemon to chose from, especially in the early game. If he wants the more 'normal' Pokemon, go with Heartgold/Soulsilver.

What does 'normal' Pokemon mean?

Closest to Satoshi Tajiri's original vision since it's a remake of the last game he directed (He was only involved for the first two generations).

But the social part is such a huge part of Pokemon, not getting him the latest version will mean he cannot really trade or fight against other kids so get him the last version.