Finally got it

[bash1010]

Some of you might remember me from a couple of years ago, that would be pretty cool. I used to come to this site a lot and when I lost my emerald I pretty much just gave up on Pokemon. I decided to pick up Diamond and I am very much impressed with the game itself. I do however feel overwhelmed that I wont be able to catch up with the competative metagame and even in-game seems a bit intimidating. Can some of ya'll please just try and calm me down and tell me how things have changed since the good ol' days of emerald?

 

[Little Green Yoda]

Skarm is no longer the #1 choice for physical walling but Blissey is as popular as ever. Go here to see what most people are using

Oh, yeah and Stealth Rock is everywhere and rightfully so.

 

[sanjay120]

There is this thing called Garchomp. Hera 2HKOs Skarm now, Zam and Gengar can 2HKO Bliss, Snorlax and Suicune are BL. Phys/special split, Stealth Rock raping everything, the new walling combo is Blisselia.

Yeah D/P is kinda overwhelming.

 

[Phuquoph]

Check the main site. The Strategy Pokedex will give you an idea what all the new and old Pokemon can do. There's also a list of all the new abilities, items and moves.