Togekiss
I would say that your best bet would be Togekiss. With a base 95 Def and one of the most balanced stats of all the normal types, Togekiss stands as a victor between the physically defensive normal types. With access to a plethora of both supportive as well as offensive moves, Togekiss is a very dangerous Pokemon to face. It's Paraflinch combo is very hard to stop once started and the fact that it has access to a reliable recovery move in Roost, Togekiss is almost a must have.
Recommended moveset
Togekiss @ Leftovers
Trait: Serene Grace
EVs: 248 HP / 216 Def / 44 Spe
Bold Nature
- Air Slash
- Roost
- Thunder Wave
- Heal Bell
*Air Slash is it's main STAB in this moveset and will also activate the Paraflinch combo once Thunder Wave has been used in succesion. Thunder Wave does not only function to activate Paraflinch but it can also be used to cripple fast sweepers that cannot afford the 4X loss in speed. Roost is just your reliable recovery move that will enable you to heal up and thus cause the paraflinch to cause more horror. Heal Bell is not only to heal itself but it's status induced teammates as well.*
Porygon2
Porygon2 is what comes to mind when you hear bulky duck. It's defensive abilities were already known to be uttermost impressive but with the release of Black and White it was graced with that item that turned the competitive world upside down, the Eviolite. With this item equiped, Porygon2 becomes one of the bulkiest if not the bulkiest normal type in the entire metagame, even pushing Togekiss of it's throne. What makes everything worse is that it has access to a reliable recovery move meaning that it will be trolling, walling and tanking for a decent amount of time
Recommended moveset
Porygon2 @ Eviolite
Trait: Trace
EVs:252 HP / 176 Def / 80 SpD
Bold Nature
- Ice Beam
- Discharge
- Toxic
- Recover
*Ice Beam is mainly to deal with Ground and Flying types as they both have proven to be highly offensive types in today's metagame. Discharge is to discourage water and flying types to switch in as well as your pseudo status inducer as it has a good chance of paralyzing the opponent. Toxic is that move that will enable you to outstall even the greatest walls, as long as they aren't steel or poison types. Every defensive behemoth likes to recover itself and Porygon2 is no exception. With Recover it can pretty much troll all day*