idk which Gourgeist you used for calcs but small sized Gourgeist counters him perfectly and heres why:252 Atk Life Orb Breloom Stone Edge vs. 252 HP / 0 Def Gourgiest: 120-142 (32.08 - 37.96%) -- 50.78% chance to 2HKO after Stealth Rock and Spikes
252+ Atk Gourgiest Phantom Force vs. 4 HP / 0 Def Breloom: 162-192 (61.83 - 73.28%) -- 25% chance to OHKO after Stealth Rock and Spikes
252+ Atk Gourgiest Shadow Sneak vs. 4 HP / 0 Def Breloom: 73-87 (27.86 - 33.2%) -- guaranteed 3HKO after Stealth Rock and Spikes
There you have it Breloom barely 2HKO-es Gougriest and only 3HKO-es it if there was no entry hazard, However, Gourgiest 3HKO-es at best with entry hazards if it has Shadow Sneak, if it using Phantom Force, then Breloom can set up Swords Dance or Substitute, Gourgiest is definitely not a Check or a counter for Breloom because it lacks healing moves, however, with Will-o-Wisp, Gougiest can be a Counter for Scarf Breloom.
- It outspeeds him and can will-o-wisp before breloom can do anything
- Any pumpkin using fireblast (which is actually a pretty decent option considering ferrothorn and other grass types and steel types give him a little trouble and it does as much as phantom force without having to take up a turn) does (43.51 - 51.9%) while a burned breloom can only manage to do (19.1 - 22.29%) with stone edge (a 5hko at best)
I think poison heal breloom is completely countered by gourgeist considering leech seed, fighting attacks, and spore don't affect pumpkin and any grass move is doing shit damage
252+ Atk Breloom Seed Bomb vs. 252 HP / 0 Def (custom): 60-72 (19.1 - 22.92%) -- possible 5HKO