>>96085843
The tau are actually a hard matchup agains't tyranids due to their ways of warfare. Tyranids are not nearly as unpredictable as orkz or humans and earth caste scientists did their absolute best to uncover parts about their nature and instincts. The main thing was that tau leadership lacked adaptability skills specially after the whole 'lets make everyone puretide' debacle but they learned that to survive the galaxy they needed to rapidly adapt their strategies. Them being able to develop technology at a faster rate than anyone else in the setting makes it so the tyranids are at a constant war for adaptability agains't a opponent that comes at closer to that particular skill of their than any other in the galaxy.
One of the few reasonable faction matchups the tau have in lore and people are out here complaining about plot armor. Bitch in Damocles Cato Sicarius took down half the fire caste battle force by himself and people just turn a blind eye to that apparently.
The tau just can't handle fighting space marines, orkz, anything chaos, necrons, eldar, dark eldar and at moat have a good matchup agains't guard regiments and bugs. Hell they have a constant fear of civil war and unrest since it's deeply taboo in their society so genestealer cults are very well a high level threat, specially since some have been confirmed to exist within tau space.