Buy-down: Expect the futures price to fall, sell through the relevant contracts, and then buy the relevant contracts at a low price after falling to the expected price, earning the difference between selling high and buying low. This is often called shorting.
Futures can be traded in both directions, and futures can be long or short. When the price rises, you can buy low and sell high, and when the price falls, you can sell high and make up low. Going long can make money, and shorting can also make money, so there is no bear market in futures.