First you're going to need a Ditto. If you don't know how to RNG for a flawless one, you're going to have a tough time, having to go on a major Ditto hunt until you find two (or one if you're lucky) suitable Ditto; one with a 31 IV for Speed, and another one with a 31 IV for Special Attack (or one Ditto with both, but that's going to take even longer). Don't throw away Ditto with a 31 IV for another stat, your goal should be to have at least one for every stat, hopefully even some with 2 or 3 flawless IVs.
Now you need a Timid synchronizer. Find a place where you can easily catch Pokemon with the ability Synchronize, and catch a Timid one. Don't throw away other natured synchronizers, keep one of every nature you find, they will come in handy if you ever want to breed other Pokemon, or catch Legendaries with the right nature.
Use the synchronizer to find a Timid Snorunt, or a compatible Timid father (Snorunt is in the Fairy and Mineral egg groups): http://bulbapedia.bulbagarden.net/wiki/Egg_group
If you don't have wild Snorunt available, breed for a female one with the Snorunt you already have, use the Ditto with the best IVs, and equip it with a Power Item to make the offspring inherit its most important IV. This will give you a set: a female Snorunt with a good IV, and a male Pokemon that's Timid. Equip the Timid father with an Everstone (50% chance of passing down nature, 100% in BW2) and the mother with the Power Item. Breed until you have a Timid Snorunt.
Now use a Ditto with another flawless IV and equip it with the right Power Item. Give the Timid Snorunt an Everstone. Breed until the offspring has two flawless stats. If you want more than two flawless stats, breed for a Pokemon of the opposite gender of the good Snorunt you already have. Aim for similar flawless IVs, but one different flawless IV. Breed those two together and so on. The more flawless IVs you want, the longer it's going to take.
When you have a Timid female offspring Snorunt with the right IVs, EV training can begin!
Go to Serebii and look for EV-training hotspots that suit your game:
http://www.serebii.net/games/evs.shtml
(scroll all the way down)
Use the Power Items, PokéRus if you have it, and Vitamins for the first 100 EVs. It's all noted in the guide. Manually keep track of the EVs it has acquired. Afterwards, get your Effort Ribbon and level it to 100.
Now apply this to the rest of your team.