If you have Ruby,it'll be easy,but if you have Sapphire,you'll need some trading...
Get a Male Zangoose and a Female Seedot.Raise Zangoose until Lv.55 or somewhere around it,so it learns False Swipe.Breed it with your Seedot,and keep breeding until you get a Male Seedot with False Swipe.
Now,get a Female Shroomish and beed it with your False Swiping Seedot.Now,hatch the new Shroomish.Afterwards,raise Shroomish,but DON'T EVOLVE IT,until level 54,and it'll learn Spore.Then you can let it evolve.
Hope this helps in any way.