My wife and I were parking the car today, and doing the usual digging for change. My wife had some dimes, I had some quarters. I knew my quarters could beat her dimes in a fight, and I told her so. This was an intuition, but of course it is backed up by the fact that quarters are both bigger and more valuable than dimes. So unless the dimes vastly outnumbered the quarters, they'd get their butts kicked if they somehow fought each other.
Of course, dime vs. quarter is not really an interesting fight, because it's so lopsided. So I got to thinking what sort of coin fights would be interesting. The first one that lept out at me was dime vs. nickel. I think they're pretty evenly matched: the nickel has a hefty size advantage, but the dime is worth twice as much. I thought about dime vs. penny, but pennies are pathetic wusses that no one wants. During my recent move, I treated pennies like dust bunnies or paper scraps left over from torn spiral bindings, i.e. as the worthless trash that they are. I recently read in the New York Times that it costs the U.S. mint 1.4 cents to make each penny. That just shows how lame they are. Its marginal size advantage against the dime in no way makes up for the repulsive insignificance that is at the heart of its very nature.
Unfortunately, I don't think there are too many more good one-on-one coin fights unless you go to some of the lesser used coins. Susan B. Anthony dollar vs. the Sacajawea dollar would be interesting. It would be a "chick fight", since both coins prominently feature women. But I'm not sure how much of the femaleness of the image would influence the coin's behavior in coin-on-coin combat. I think the Sacajawea dollar would win, unless the SBA dollar could trick its opponent into thinking it was a quarter. I doubt this fight would happen though, because the only place I encounter these coins is when getting change from a vending machine in the post office. And despite the myths about "going postal", etc., the post office is usually a pretty sedate place. It would be nice to have some entertainment while waiting to pick up a package though.
The Kennedy half dollar would be a good opponent for either of the dollar coins, creating a dynamic similar to dime vs. nickel. No doubt someone who knew more about coins than me could come up with some great matchups, especially when foreign coins (which often can have higher values than US coins) are considered.
But then, the whole topic now strikes me as rather pointless, since coins can't actually fight each other.