For something completely different, I present my:
Gargantuan half-celestial, half-dragon (gold), axiomatic black pudding
[Based on my CR12 pudding smack from the Sultans of Smack...]
I haven't really worked on the character classes on this smack, just went for the forsaker for the SR. This removes all those nifty half-celestial spells, so if you find another way to get SR, that's probably even better....
You only need items for your forsaker abilities. To make this even better you need anti-magic, you could possibily do this with your mount, or take leadership and go for followers with anti-magic.
It's of course very silly, but I guess that is what we are aiming for here

And it
is legal by the rules.
Strong points: Immune to all weapon damage. Immune to all elemental damage (except sonic with 20 resistance). Immune to lots of other spells (mind, fear, etc.). SR 45. Can fly (40-good). Almost all abilities are (Ex), works equally well in an anti-magic field.
Weak points: Vulnerable to death effects if SR is beaten. Very slow, crap AC (but this doesn't matter much). Only average saves.
Tactics: Try to be hit as many times as possible with weapons (splitting into several puddings). Kill magic users, you are unkillable in melee. If you find some anti-magic, you'll win.
Gargantuan half-celestial, half-dragon (gold), axiomatic Black Pudding Pal10, Forsaker 10 : CR 36; Gargantuan outsider; HD 30D12+30+10D12+10D12+500; hp 855; Init -4; Spd 20, fly 40 (good); AC 21 (-4 size, -4 Dex, +19 natural); Melee slam +58/+53/+48/+43/+38 (2d8+20 + 2d6 acid), bite +56 (2d8+10+ 2d6 acid), 2 claws +56 (2d6+10+ 2d6 acid); SA smite evil, smite chaos, breath weapon, turn undead; SQ improved grab, acid, constrict, split, blindsight 60', darkvision 60', lowlight vision 60', immune to mind influencing effects, poison, sleep, paralysis, stunning, polymophing and critical hits [from ooze], linked minds, sonic resistance 20, fire immunity, cold immunity, electricity immunity, aura of courage, special mount, fast healing 3 (50), forsake magic, DR 11/+5, magic destruction, tough defence, natural weapons (+5), slippery mind; Face/Reach 10 ft by 40 ft / 15 ft; SR 45; AL LG, SV Fort +41, Ref +17; Will +22: Str 51, Dex 3, Con 30, Int 7, Wis 5, Cha 7
Feats: Great Fortitude, Iron Will, Lightning Reflexes, Multiattack + 8 more
Skills: 38*6+10+10= 228 points
SA–Smite Evil (Su): 1/day, deal an additional +20 damage against an evil foe.
SA–Smite Chaos (Su): 1/day, deal an additional +20 damage against a chaotic foe.
SA- Breath Weapon (su): 1/day, Cone of Fire, 6d10 damage (Ref DC20 for half).
SA–Turn Undead (Su): 1/day, the creature can attempt to turn undead creatures.
SQ- Improved Grab (Ex): To use ths ability, the half-celestial, half-dragon (gold), axiomatic black pudding must hit with its slam attack. If it gets a hold, it can constrict.
SQ- Acid (Ex): The half-celestial, half-dragon (gold), axiomatic black pudding secretes a digestive acid that dissolves organic material and metal quickly. Any melee hit deals acid damage. The pudding’s acidic touch deals 50 points of damage per round to wood or metal objects. The opponent’s armor and clothing dissolve and become useless immediately unless they succeed at Reflex saves (DC 19). The acid can dissolve stone, dealing 20 points of damage per round of contact. A metal or wooden weapon that strikes a half-celestial, half-dragon (gold), axiomatic black puddingalso dissolves immediately unless it succeeds at a Reflex save (DC 19).
SQ-Constrict (Ex): A half-celestial, half-dragon (gold), axiomatic black pudding deals automatic slam and acid damage with a successful grapple check. The opponent’s clothing and armor suffer a -4 penalty to Reflex saves against the acid.
SQ-Split (Ex): Weapons deal no damage to a half-celestial, half-dragon (gold), axiomatic black pudding. Instead the creature splits into two identical puddings, each with half the original’s hit points (round down). A pudding with only 1 hit point cannot be further split.
SQ–Linked Minds (Ex): Half-celestial, half-dragon (gold), axiomatic black puddings within 300 feet of each other are in constant communication. If one is aware of a particular danger, they all are. If one in the group is not flat-footed, none of them are. No half-celestial, half-dragon (gold), axiomatic black puddings in the group are considered flanked unless they all are.
SQ–Immunities (Ex): Immune to mind-influencing effects, poison, sleep, paralysis, stunning, and polymorphing. Not subject to critical hits.
SQ–Blindsight (Ex): An ooze’s entire body is a primitive sensory organ that can ascertain prey by scent and vibration within 60 feet.
SQ- Aura of Courage (Ex): Beginning at 2nd level, a paladin is imune to fear (magical or otherwise). Allies within 10 feet of the paladin gain a +4 moral saving throw against feat effects.Granting the moral bonus to allies is a supernatural ability.
SQ- Special Mount (Ex): Upon or after reaching 5th level, a paladin can call an unusually intelligent, strong, and loyal steed to serve her in her crusade aginst evil. This mount is usually a heavy warhorse or a warpony.
SQ- Fast Healing (Ex): Forsakers regain hit points at an exceptionally fast rate. At 9th level, the forsaker regains 3 hit points per round, to a maximum restorable per day of 50.
SQ-Forsake Magic (Ex): The forsaker must avoid all use of spellcasting, spell-like abilities and magic items. The forsaker must also refuse any benefits from others magic.
SQ-Spell Resistance (Ex): Axiomatic creatures have spell resistance equal to double the creature's HD (maximum 25).
SQ-Spell Resistance (Ex): At 1st level, the forsaker gains spell resistance 11. This value increases by +1 with each level, and stacks with any other applicable spell resistance he has.
SQ-Damage Reduction (Ex): At 2nd level, the forsaker gains damage reduction 3/+1. This damage resistance rises with 2/+1 for every two forsaker levels he gains thereafter. The ability remain in effect only as long as the forsaker destroys the required value of magic items (100 gp per points of damage reduction) every 24 hours.
SQ-Tough Defence (Ex): At 3rd level, a forsaker gains a natural armor bonus equal to his Constitution monus (if any).
SQ-Natural Weapons (Ex): Beginning at 3rd level, the forsaker can fight as though he and his weapons were one. Any weapon he uses functions as if it were a natural weapon for overcoming damage reduction.