If you include HP which is slightly different to the other stats, the highest is Blissey's HP which can get to 714.
Otherwise it's Shuckle who can have a maximum Defense or Special Defense of 614.
And just to complete the stats, the Deoxys forms can have the highest Attack, Special Attack or Speed, with a maximum of 504.
Oh, and with stat boosts you can go +6 stages which is 4 times the original, so Shuckle can get to 2456.
A Choice item can boost Attack, Sp.Attack or Speed by 1.5x, so Deoxys can get to 3024!
You can go to the links to check if they learn moves to boost those stats, Shuckle's defense and Deoxys's Special Attack can definitely be boosted so you can get that 3024.