Lol. I don't think any deck is over-powered. Or rather, the structure of any deck. I've beaten Sliver decks as many times as I've won with them. Maybe it's just because I'm so damn good. ;P
Well, Onizaru, my solution is a simple one. If I take a sliver deck to combat yours, I add in Sliver Overlords and simply bide my time stale-mating our cards. A sliver queen, with the ability to give me a vaster range of slivers, will also give me the upper-hand.
But there are innumerable strategies against sliver decks without actually using them. They're rather easy to defeat. Would you like to "game?" in a sense? Textually, albeit, but perhaps it'll work. You can pick some sliver deck and I'll defeat it.
I can beat any deck given the time. One loss will equal an infinite number of victories. Until a new deck to oppose me has arisen.
Soth, those words are to you. I'm serious. I bet you I can defeat any sliver deck you throw at me. Just give me twenty minutes, free choice of my cards to pick and I'll beat it. My favorite is using 3K cards to bash slivers.