To get a turbo start at the start of a race, wait for the announcer to count down "3... 2... 1...", then wait for him to say "GO!". As soon as he does, tap L1 (Boost) to speed off the starting line.
Stealing Kart bodies:
To get a Kart body that you have not previously unlocked, download another player's Kart that uses the desired body design. You can edit their Kart and save it for your own use.
United front sticker:
Go to "Car Create" mode and try placing a sticker. Zoom all the way out and move the view around until you find a hidden "United Front" sticker on the right.
Select to edit your car, then select any sticker and move it around. Use the right Analog Stick and look down at the car. Rotate the camera until you see the sticker on the overhead light.
Warp Boost hint:
Whenever another racers uses a warp portal, you can go through the open portal and warp together with the racer that used it.
Anonymous - Play an online race.
Newcomer - Complete the qualifier race.
Mechanic - Create a kart in Kart Studio.
Sculptor - Create a track in Track Studio.
Dresser - Create a Mod in Mod Studio.
Shopping Spree - Enter the Shop.
Getting To Know You... - Invite 5 unique friends to an online race.
Fill'er Up - Fill your boost meter.
Knockin' Boost - Drive over 100 boost pads.
ModSpot Explorer - Visit all the locations in ModSpot.
Headspinner - Do a 1080 spin and land successfully.
Taster Session - Try all the game modes in Single Player Race.
Showing The World - Win 10 online races.
Trigger Happy - Use all the weapons in the game.
Fast Learner - Complete all the race tutorials, and watch all the video tutorials.
Offering Opinions - Rate 10 tracks, 10 Mods, and 10 karts.
Pioneer Racer - Be part of the first race on a published track.
Drifting Superstar - Earn 100,000 drift points in one drift.
The Drifter - Drift 1,000 times in total.
Slow and Steady - Win an action race without using any boost or using a boost pad.
Pacifist - Win an action race without firing any weapons.
Remixer - Remix a character, a kart, and a track.
Series Winner - Win a ranked race series.
ModNation Prospect - Earn at least 1,000 Total XP (including Race XP and Create XP).
Say Cheese! - Use photo mode in a race, in a studio, or in the ModSpot.
Beat Down - Win your first online action race on a particular published track.
Bruiser - Get a total of 200 takedowns.
Aggro Racer - Sideswipe 75 opponents.
Sharing Karts - Publish a kart and have at least 10 people download it.
Sharing Mods - Publish a character and have at least 10 people download it.
Sharing Splines - Publish a track and have at least 10 people download it.
Mayhem Tour Winner - Win the Mayhem Tour.
Range Tour Winner - Win the Range Tour.
Grim Tour Winner - Win the Grim Tour.
Third Eye - Hit 20 opponents with weapons dropped as secondary weapons.
Shields Up! - Successfully defend yourself with your shield 20 times.
Flaming Hot! - Get in the top 10% in Hot Lap Mode on any given day.
Join the Team - Beat all 28 developer lap times in career.
ModNation Star - Earn at least 5,000 Total XP (including Race XP and Create XP).
Level of Merit - Complete all the career challenges.
Hoarder - Collect all the tokens in the single player career.
Taking On The World - Win 100 Online Races.
Win Grand Finale - Win the Grand Finale.
Elite Hunter - Beat all the Elite racers in the grudge matches.
Dominator - Come 1st in every race in the career.
Star Creator - Earn at least 250,000 Create XP.
ModNation Superstar - Achieve level rank 30.
ModNation Legend - Earn all Bronze, Silver, and Gold trophies.
"Arctic Tour" trophies:
The Mighty Deflector - Use your shield to defend against a Bolt Storm on Snow Storm City.
Air Defense - Use your shield to defend against any attack whilst in the air on Downhill Peak.
Dance Party - Hit three opponents with a single Sonic Bomb on Iceberg Edge.
Arctic Promoter - Host a casual race using a UFG track from the Arctic theme.
Arctic Creator - Create and publish a track using the Arctic theme.
Arctic Tour Winner - Win the Arctic Tour.
Ice Cool Champion - Come 1st in every race, collect all the tokens, and complete all the race objectives in the Arctic Tour.
"Big City Tour" trophies:
Speeder - Use a Supercharger and for the duration of the boost don't hit a wall on Tourist Trap.
Mind The Mine - Hit an opponent with a level 1 secondary weapon on Gridlock River.
Air to Air Combat - Hit an opponent in the air with a Swarm on Skyscraper Hop.
Big City Promoter - Host a casual race using a UFG track from the Big City theme.
Big City Creator - Create and publish a track using the Big City theme.
Big City Tour Winner - Win the Big City Tour.
City Slicker - Come 1st in every race, collect all the tokens and complete all the race objectives in the Big City Tour.
"Far East Tour" trophies:
Ricochet - Ricochet a Straight Shot then hit an opponent on the Great Wall track.
Shocker - Hit three opponents with a single Chain Bolt on the Fortress track.
Coat Tails - Follow an opponent into his or her Warp on the Terraced Drop track.
Far East Promoter - Host a casual race using a UFG track from the Far East theme.
Far East Creator - Create and publish a track using the Far East theme.
Far East Tour Winner - Win the Far East Tour.
Undisputed Champion - Come 1st in every race, collect all the tokens and complete all the race objectives in the Far East Tour.