You actually have plenty of physical defense already. Like Liberal Army pointed out, Rotom-W makes for a good one (and physically defensive Rotom-W is one of the most common ones these days because of Talonflame and Mega Pinsir). Here's a another set to consider:
-Rotom Wash w/Chesto Berry
Nature: Bold
Ability: Levitate
EVs: 252 HP, 252 Defense, 4 Speed
Moves: Hydro Pump, Volt Switch/Thunderbolt, Rest, Will-o-Wisp
Gliscor is also a great physical wall, and Scizor's physical bulk is decent too. What you really need is a specially based Pokemon. All of your current pokes are more or less physically based. You can roll with Gastrodon like Liberal Army said. You also mentioned Vaporeon. It's good, if you know how to use it:
-Vaporeon w/Leftovers or Lum Berry
Nature: Bold
Ability: Water Absorb
EVs; 252 HP, 248 Defense, 8 Sp.Defense
Moves: Scald, Wish, Protect, Toxic
Stallin' mixed wall machine she is.
Anyway, other specially based pokes to consider are:
-Clefable w/Leftovers
Nature: Calm
Ability: Magic Guard
EVs: 252 HP, 132 Defense, 124 Sp.Defense
Moves: Moonlight, Moonblast, Aromotherapy, Toxic/Ice Beam/Flamethrower
-Goodra w/Assault Vest
Nature: Modest
Ability: Gooey/Sap Sipper
EVs: 252 HP, 252 Sp.Attack, 4 Defense
Moves: Draco Meteor/Dragon Pulse, Flamethrower, Focus Blast, Thunderbolt/Sludge Wave
-Togekiss w/Leftovers
Nature: Calm
Ability: Serene Grace
EVs: 252 HP, 252 Sp.Defense, 4 Sp.Attack
Moves: Air Slash, Thunder Wave, Roost, Dazzling Gleam
To add, here's a more effective Assault Vest Goodra. Dragon Tail gives the team some form of phazing; Earthquake makes Goodra much less vulnerable to Heatran, as it can take a Focus Blast more easily than an Earthquake:
-Draco Meteor
-Fire Blast
-Thunderbolt/Earthquake
-Dragon Tail/Earthquake
Nature: Quiet/Sassy
EVs: 248 HP/252 SAtk/8 SDef
Item: Assault Vest
Ability: Gooey/Sap Sipper
Wash Rotom should use 44 Speed EVs to outspeed the occasional Jolly Azumarill.
Togekiss has alternative options besides Dazzling Gleam:
-Thunder Wave
-Air Slash
-Defog/Heal Bell/Aura Sphere/Flamethrower/Dazzling Gleam
-Roost
Nature: Calm
EVs: 248 HP/8 Def/252 SDef
Item: Leftovers
Ability: Serene Grace
And to add, Infernape and Scizor sets:
Infernape:
-Fire Blast/Flare Blitz
-Close Combat
-Thunder Punch
-Hidden Power (Ice)/Grass Knot/Mach Punch
Nature: Hasty/Naive
EVs: 168 Atk/88 SAtk/252 Spe
Item: Life Orb
Ability: Iron Fist
Scizor:
-Swords Dance
-Bullet Punch
-Knock Off/Bug Bite/X-Scissor
-Roost
Nature: Adamant
EVs: 248 HP/136 Def/104 SDef/20 Spe
Item: Scizorite
Ability: Technician
or
-Swords Dance
-Bullet Punch
-Bug Bite/U-turn/X-Scissor
-Knock Off/Superpower
Nature: Adamant
EVs: 252 Atk/4 SDef/252 Spe
Item: Scizorite
Ability: Technician
or
-U-turn
-Bullet Punch
-Superpower
-Knock Off/Pursuit
Nature: Adamant
EVs: 248 HP/252 Atk/8 SDef
Item: Choice Band
Ability: Technician
or
-Defog
-U-turn
-Bullet Punch/Knock Off
-Roost
Nature: Impish
EVs: 248 HP/252 Def/8 SDef
Item: Scizorite