I have a 96 C280 sport and it can be a pain to take off sometimes in the rain sometimes. It seem that only the right rear tire is getting power ...

Any ideas to what I should start looking at ?

 

I wouldn't look too far. This is pretty normal in the rain. At least, my '05 C230K does the same thing.
The roads are fairly slippery if it has been some time since it rained, as it is here, and I find the right rear
tire buzzing a bit if I don't just take off slowly. I personally don't think there's anything "wrong" with your car.
But I could be wrong.
I've been wrong so many times in my life, it's refreshing when I'm accidentally right once in a while.