Secret Agent Clank

First, go to the "Special" menu with any character. Then choose "Check Size Matters Save". If the game detects a Size Matters save on your memory stick, several free skins will be unlocked, and are accessible via the "Skins" menu. They will cost you no Titanium Bolts.

In the Treehouse, go to a desk near the "Robot Finds Kitten" message. On this desk is a picture of someone. Go to this picture, and press Circle(2), Triangle, Circle, X. You will be shown a platform with a fountain, fireplace, angels, kittens, and roses. There is also a message about TJS's mother. This platform is a memorial for an HIG crew member's mother.

Go to the Treehouse and enter the cheat Up, Up, Down, Down, Left, Right, Left, Right in the area where you find the Chalice.

Spend the indicated number of Skill Points to unlock the corresponding cheat option.

Big Headed Clank: 4
Big Headed Ratchet: 8
Mirrored Levels: 12
Weapon Switching: 16
Big Headed Enemies: 20
Super Bloom: 24
Old Timey: 26
Expat Exchange: 28
Bolt Confusion: 32
Pumpkin Heads: 40
Snowman Heads: 45
Kapow: 50
Ratchet Pack: 65
Hardcore Mode: 65

Use Skill Points to get these cheats.

Complete the following tasks to unlock the corresponding Skill Point.

52 Card Pickup: Rionosis: Quark vs Jack - Finish off Jack using only cards, not bombs. Punches can be used.
A Gadgebot Stands Alone: Les Paradis Des Tricheurs Casino: Special Missions: Gadgebot part - Never use the revive command in either of the Gadgetbot arenas.
A Pretty Good Likeness: Defeat Klunk without damaging Robo-Ratchet.
All Slime Must Burn: Secret Laboratory Venantanio - Complete the level killing Amoboids using only melee attacks and the Suitcase Flamethrower.
Antaeus: Prison Planet - Complete the Mega-Challenge without jumping.
Black Diamond: Glaciara: Snowboard Clank - Hit no obstacles (enemy projectiles do not count).
Black Tie Affair: Asyanica: Clank - Get through the level defeating all enemies with the Tie-A-Rang.
Blaster Overload: Asyanica: Quark - Defeat the Boss without using the regular blaster.
Cereal Decoder Ring: Complete the Knockin' On Klunk's Door challenge with a time less than 4:30.
Deadly Hands: Rionosis, Clank - Dispatch all of the Kingpin's guards before he reaches the fourth tourist cart.
Deep Six: Canals, Venantonio: Special Missions - Do not get hit by seeking mines.
Dress for Success: Rionosis: Quark vs Jack - Get Jack to hit himself with three of his own hats.
El Dia de los Muertos: Fort Sprocket: Gadgetbot mission - Get a Static Midge helmet on all three Gadgebots at once.
Empty the Warrens: Prison Planet: Cafeteria - Kill over 89 Tyhrranoids in the Tyrranoid Recycling challenges.
Furious Fists Of Fury: Boltaire Museum - Use only your melee attacks to complete the level.
Hanging Judge: Prison Planet: Jail Break - Complete the main challenge without letting any prisoners escape.
He Cleans Pools Too!: Hydrana: Cowboy Quark - Kill 20 enemies with a single lawnmower.
I Kill The Rock: The Quasar Fields, Giant Clank - Kill all three Mega Rock class dreadnoughts.
Indian Burn: Prison Planet: Exercise Yard - Kill ten enemies with dodgeballs.
Inverse Ninja Law: Asyanica, Quark - Kill 99 ninjas during the fight.
It's A Delicacy Somewhere: Spaceship Graveyard: Clank's Mission - Blow up every mature organic spore in the level "Ones That Aren't Rooted").
Like the Wind: Asyanica: Clank - Get through without getting hit by anything.
Magnum Opus: Complete the entire opera without getting hit.
Master Of Disguise: Kingpin stealth level - Use every disguise station when the Kingpin gets suspicious (do not kill the last guard until the end).
Modestly: Do not lose the towel ever in the Mega challenge.
Offensive Driver: Hydrana car mission - Complete the timed challenge with at least 60 seconds remaining.
Perfect Chrome Finish: Complete the Rescue Clank! challenge without any Gadgebot taking any damage.
Perfect Tango: Glaciara, Clank - Do not miss any button presses on the tango music segment.
Punchy: Spaceship Graveyard: Quark - Destroy all pirates using only punches.
Ring Around The Rosie: Hydrano, Clank - Collect all the rings in the Driving Test Ring challenge.
Ringleader: Glaciara: Clank Snowboarding - Collect all the rings in the Go For The Gold ring challenge.
Ringmaster: Canals, Venantonio: Special Missions - Collect all the rings in the Threading The Needle challenge.
Robot Finds Ninja: Asyanica: Clank - Get all possible stealth kills in the level (one sleeping and several before the second row of police cars).
Ruuba Dub Club: Use the wrench to kill the Amebiod King.
Silent Night: Boltaire Museum, Clank - Take all guards in the museum using stealth takedowns.
Slippery Slope: Hydrana: Clank - Hit at least five oil slicks on a single life.
Smooth Moves: Snowboarding level - Get 15 guards to shoot each other (brake when they are about to shoot).
Sold Out: Get 150,00 box office sales.
Sour Victory: Spaceship Graveyard: Quark - Kill the Kudzu Monster using only lemons.
Speed Demon: Complete the Rescue Clank! challenge with a time of 1:25 or less.
Steel Rain: Rionosis: Clank - Send at least 10 Henchbots of the Dondolas into the open blue.
The Law Can't Touch Me: Prison Planet: Exercise Yard - Complete the Mega Challenge and never get struck by the yard guns.
Trash Talk: Kingpin stealth level - Use the trash cans to lure the guards and kill them (hit the cans when Kingpin is close, hide, then kill the investigating guard)
Triple Platinum Record: Boltaire Museum, Clank - Get through the entire rhythm segment without missing any button presses.
Turn The Tables: Underwater Base - Complete at least four successful takedowns on Klunk and never get taken down yourself.
Twinkle Toes: Venantonio: Quark's Musical - Get a 5-chain butterfly bounces without touching the stage.
Wake Of Destruction: Destroy everything.
Whip It Good: Prison Planet: Jail Break - Get 40 kills with the plasma whip.
Yeeee Haaaaaw!: HYDRANAracing - Perform a roll off of a cliff.

Type the code Left, Left, Right, Up, Down, Down, X in the pause menu.