Stealth Rock - fairly self explanatory. accounts for the viability and inviability of so many pokemon. strategies to put it up, take it out, etc. Hidden Power - how did this topic go this far with no mention of this move? hidden power is the sole reason many pokemon are even usable. Magnezone would be **** without Hidden Power, as would be many special attackers with otherwise lacking coverage options. Volt/Turn - Can't decide on one, so i'll group them together. Major annoyances, but seriously effective means of gaining control of the battle. A big factor in why Genesect is in suspect testing.
After this i'm slightly BSing.
Will-o-Wisp - Residual damage is never fun, but Will-o-wisp does more than just 12.5% per turn. Will-o-wisp's attack drop stops the vast majority of physical attackers dead in their attempts to sweep. Scald is similar to will-o-wisp, but trading the chance to burn for guaranteed immediate damage. Not to mention giving a burn option to bulky water types. Spore - Sleep is annoying, especially with the new sleep mechanics. Spore's guaranteed sleep certainly is rage inducing. Spore takes some otherwise average pokemon and gives them huge utility. Superpower - Fighting is a very strong offensive type. i think this move merits mention due to its wide availability and high power. it's a very effective coverage move that many pokemon love having. --- Heh heh... the wind... it is... blowing...
Stealth Rock is huge. Stealth Rock weakness helped drive Ice-types the hell out of OU. Rock-weak Pokemon need to be able to overcome that 25-50% HP drop in order to see regular use.
Earthquake is definitely a big one. People say that Ground-type attacks aren't as prominent these days, but they still stick Air Balloons on anything with a Ground weakness anyways.
Volt Switch and U-Turn, as noted, are annoying-as-hell mindgamey safe-switch moves. Definitely a large part of the current metagame.
Toxic is and always has been a key move for beating walls and setup sweepers alike. Practically every major wall nowadays either has to be a Steel-type or have an ability that prevents or cures Toxic. --- I claim to be the official Porygon2 of the Pokemon Black 2 board. Scientist MileRun: WaRy associate