Hidden Characters:
Race as Mr. Herbert Garrison
Activate all four checkpoints on the Rally Days 2 race.

Race as Pip Pirrup
Only activate checkpoints one and four on the Rally Days 2 race.

Race as Bebe Stevens
Lose the Cowdays race without collecting any health pick-ups.

Race as Shelly Marsh
Collect the three hidden pick ups in the Valentine's Day race. The first two are located at each tower. The third is found behind the Skater picture in the jungle.

Race as Mr. Mackey
Win the Spring Cleaning race.

Race as Tweak
Collect five caffeine pick-ups in the Spring Cleaning race.

Race as Eric Cartman Cop
Hit Chicken Lover five times with the salty balls in the Read-A-Book Day race.

Race as Scuzzlebutt
Not available in this version

Race as Sheila Broflovski
Not available in this version

Race as Liane Cartman
Not available in this version

Race as Big Gay Al
Win the Pink Lemonade race.

Race as Visitor
Collect the hidden pick-up above checkpoint one and the another pick-up that is between check point four and the wood bridge in the Memorial Day race.

Race as Ike Broflovski
Collect the hidden pick-up on top of the airplane in the Memorial Day race.

Race as  Dr. Alphonse Mephisto
Win the Independence Day race.

Race as Ned
Collect thirteen turbo pick-ups  in the Independence Day race.

Race as Death
Win the race Halloween race after only dropping off four candies at a time.

Race as Grandpa Marsh
Win the Halloween race.

Race as Starvin Marvin
Lose the Thanksgiving race without collecting any turkeys.

Race as Jesus
Win the Christmas race.

Race as Terrance and Phillip
Collect the four hidden pick-ups in the Christmas race.

Race as Satan
Win the New Year's Eve race.

Race as Damien Thorn
Win the New Year's Eve race and be the only racer to touch the millennium key.

Others:

Cheat sheet option - Don't pick up any pick- ups and beat the Rally Days 1 race
Random checkpoint option - Complete Championship Mode
Random track option - Complete Championship
Speech test option- Complete Championship Mode

I think this is a pretty good guide, you are pretty through with it and you give good information and descriptions in your walkthrough. I like the way you break it down and explain it in depth. I think you put a lot of effort and dedication into making this which is really good and also really important in a guide.

You do a good job of breaking things down and being thorough with your guide which is good. Keep up the awesome work and keep making more helpful guides! This is very good and it will definitely help a lot of people playing the game, keep up the great work!

Except that this is taken from gamefaqs. You tweaked a few things, but everything here is the exact same sentence as gamefaqs, except for the change of 1 word. The first suspicion is how almost all of them are a change of a single word or switching a single pair of words. but the real tip off is that there is a chunk that is completely word for word and the order wasn't even changed. This is your warning.