Supports are OP

IS a top... not a support.

Know your opponent.

If you've played any amount of ARAM, you should know Blitzcrank and Sona can be crazy damage dealers. Blitzcrank is a Tank/Fighter, and Sona is a Mage. Most characters can function as their secondary role, and these two are no exception.

Soraka... really? Dude, if you're having trouble with a Soraka solo, you need to practice more against bots or something. I could maybe see her being a threat if she got a Lich Bane, but even that's a stretch. Starcall is dodgeable, and you should be able to get out of her silence before it roots you.

Nidalee is primarily a Mid/Top. People take her support when they want a kill lane.

Nunu is primarily a Jungler. People take him support for a slow and bloodboil.

Play support then.

Or learn how to fill your role properly =P

The enemy supports are obviously doing their jobs.

Nidalee support is about as shit as vel'koz support or veigar support. Just because has one cc move or a heal does not make them a support.

Blitz (my main) maybe you should try to play him before you call him op. His CD's (as far as other cc's or supports go) are average or even longer. Considering that he is skill shot based, if you cant land his hook you are useless. Hook too much and oops you are now OOM. Ult to early and consider any play you were making lost. Blitz, especially from what i've seen in higher tiers, is easily beaten. Because basically it is blantently obvious when he is going to hook unless he is a good blitz. It sounds to me like you have either met a few good blitz's or you need to learn how to counter play blitz. To counter play blitz you have a few options. Bait his hook. Anyone with half decent mobility (IE adc's) can easily dodge his hook. Also learn to position yourself better in lane. Always keep minions in between you and him. And if the wave is cleared, either keep your eye on him and watch for sudden aggresive or changes of movement, or back up. His hook really doesnt have that long of range. Now the big one. A good blitz if getting beaten in lane will let you push to tower. This is him setting you up. ESPECIALLY when you are at tower is when you need to be careful, as i assume you have seen a good blitz pull you into tower and let you get eaten up by those pesky lazers.

Countering blitz is easy. Its all about positioning yourself smartly in lane, and watching him. Blitz players are easy to read most of the time. Learn the patterns and know what signals they give when they are about to hook. It's a lot more productive than the age old "OMG nerf (insert champion here)"