To get new outfits for Kratos, you must first complete the game in easy, normal or hard difficulty setting, afterwards you will unlock numerous things in the treasures screen at the main menu. you will unlock god challenges, you must complete the 10 missions for the god challenges to unlock new outfits for Krattos, the outfits give different attributes for him such as this,

Chef of War
Damage Power 100%
Defense Power 100%
Magic 300%
Health 150%
Experience 100%

Bubbles
Damage Power 50%
Defense Power 100%
Magic 150%
Health 300%
Experience 100%

Tycoonius
Damage Power 200%
Defense Power 400%
Magic 100%
Health 100%
Experience 400%

Dairy Bastard
Damage Power 50%
Defense Power 100%
Magic 200%
Health 200%
Experience 200%
BONUS: Dairy Bastard has infinite magic supply.

Ares ArmorM
Damage Power 200%
Defense Power 25%
Magic 100%
Health 200%
Experience 200%