I wouldn't really say that Chesnaught 'hard counters' either Excadrill or Tentacruel. It can take Tentacruel's attacks, but really can't do much in , doesn't appreciate being poisoned or burned. You'll also find far more Excadrill utilising Iron Head due to the increased popularity of Gourgeist, Trevenant and Togekiss, which presents a 2HKO. Depends on what tech Breloom is running. It fares pretty well against the Life Orb set, since it can threaten Breloom out if it switches in on Mach Punch, Bullet Seed, Spore or Rock Tomb, but risks being 2HKOed if it comes in on Swords Dance, whilst CB Techniloom 2HKOs with either Superpower or Power Up Punch. Unless Chesnaught is running Poison Jab or Aerial Ace, it cannot OHKO in return, so it's a decent switch in, but it does take some prediction on your part to utilise effectively.