Breloom

Once the highest DPS option among Fighting Types, Breeloom has fallen from grace with the advent of the type's power-creep. At this point, Breloom can be seen as viable, but sub-optimal for many uses. The same story plays out for its Grass Type performance, where it's still a good non Shadow/Mega of the type, but even then it's far from the lead. Sadly, Breloom has plainly fallen from grace.

Best PvE Offensive Moveset

• Counter should be paired with Dynamic Punch; this is Breloom’s preferred moveset.
• Grass Knot  should be paired with Bullet Seed or even Counter for the best Rock-type coverage.
• Bullet Seed can be paired with Seed Bomb as a second pick
• Sludge Bomb offers no offensive utility.

Best PvE Defensive Moveset

• Counter hits substantially harder than Bullet Seed, despite both being heavily resisted by Breloom’s counters.
• Sludge Bomb has 2 bars, good neutral coverage, and an early dodge window, making it optimal for defense.
• Dynamic Punch hits hard if not resisted, while Seed Bomb takes less energy than Breloom’s other charge moves.
• Grass Knot is also a good option

Counter is a great Fast Move for PvP, use it and abuse it. 

Seed Bomb is a relatively low cost charge move that can be used often to shield bait. While Grass Knot is a much more powerful move, Breloom might not be able to use it enough due to its fragility. Sludge Bomb gives Breloom an option for some coverage while Dynamic Punch makes it more of a specialist.