Select Green Team Stage 1 Race 4 and follow the snowball downhill. It will eventually jump to your right side, back to the left, then to the right again. Watch where it drops down and crosses the road back to the left. It will cross close to the road just where you go over a jump. This is the location you need to be at to get hit. Restart and make sure you get to that location just before the snowball arrives.
Easy "Chaining Cats and Dogs" trophy
Select Green Team Stage 3 Race 2 to drive on a small oval with lots boost pads. Continuously drive in circles hitting as many pads as possible while avoiding crashes.
Easy "Oh Chute!" trophy
Use the soft dirt at the edges of the track to bleed off speed. Get off quickly or it will slow you down too much. During your final approach to the finish line, zigzag as needed to take off any excess momentum.
Easy "So Many Tokens, So Little Time" trophy
Every token in the event must be collected on the same run. Once a token is collected, it is removed permanently and cannot be attempted again on a retry. Select Blue Team Stage 2 Race 2 or Blue Team Stage 6 Race 2 and drive carefully to avoid falling off the track. If you happen to fall off near a token, reverse slightly to collect any tokens that spawned in front of.
Easy "Speed Demon" trophy
Complete all events to unlock everything in Free Roam mode. Select a vehicle, then turn slightly to the right to find the two large walls that are used for wall drifts. Drive between them to find a hole in the ground. Enter it and drive through the underground passage to reach the speeddome Slowly reverse into a boost pad and keep [Reverse] held. Your vehicle will move back and forward a few times before stopping on the edge. Keep [Reverse] held until the trophy is earned.
Easy "The Complete Package" trophy
Do not use the pause menu to restart an event. If failure is imminent you must either finish anyway, wait for the timer to expire, or exit the event. You can then retry. The normal restart has the three second countdown, while the quick restart does not.