There's an alternative to having to buy a pair of big channel-locks to remove those big basket strainer nuts. The nuts are usually molded with 6 or 8 wing-like protrusions sticking out. Just place the blade of a reasonably hefty straight slot screwdriver against one of those wings and give the handle a couple of raps with a hammer or rubber mallet. That'll break the seal and you can loosen it the rest of the way by hand.