If something is the very best of its kind, it's unequaled. Your Ultimate Frisbee team is unequaled in your state this year — you've won every single game.
People who hold records for being the fastest, strongest, or smartest at something can be described as unequaled, since there's no one as good at what they do. In other words, no one equals them, or matches their ability. If you win the town barbecue competition year after year, your hot wings are unequaled. Synonyms for this adjective include peerless, unmatched, and unsurpassed.