This page looks accurate. All of the weaknesses and resistances look good, and the base stats are the same as Pokemon Database's: http://pokemondb.net/pokedex/zygarde
Keep in mind that the games are still fairly new, so the base stats are still only reasonable estimates. However, they should be very close to the actual base stats.
By double weakness, it means it takes 4x damage from ice because both types are weak to ice.
Because dragon is super-effective against dragon and ground does not resist dragon, zygarde has a weakness to dragon.
Hope I helped!
