Breloom and Parasect are the only Pokemon who learns spore and false swipe. Breloom is obviously better.
Spore will always hit (assuming no evasion raising or accuracy lowering shenanigans are in play). Sleep gives a higher catch bonus than poison, paralysis or burn so it's better for catching Pokemon. False swipe will lower them to 1hp. False swipe can never ko, so it's perfect for weakening Pokemon.
Foor your moveset, I'd recommend spore and false swipe (duh), as well as seed bomb and maybe rock tomb/slide for hitting non-shiny flying and fire types.
For a held item, run toxic orb. If you have the ability poison heal, you will gradually restore hp so you don't need to use your own stash of full restores. It also prevents breloom from getting statused.
Look out for Pokèmon with recoil moves and happy hunting!