I SUPPOSE Bell and its Healer Ability, combined with its Ground and Electric and Water resists are useful.
Other than that, it benefits from infinite Drought, but perhaps its most noticable niche is utilizing Swords Dance. Bellossom is benefited with the likes of Leaf Blade and a more powerful Drain Punch to sock Ferrothorn silly with (if not using HP Fire).
Plus, that Nature Power for Heatrans
Also, a daring fourth move is Sleep Powder or Stun Spore to catch the Volcarona who try to set up on you!