While in any park, press Square, Circle, Triangle, Square, Circle, Triangle, Square to unlock all parks.
All rides
While in any park, press Square, Circle, Triangle, Square, Circle, Triangle(2) to unlock all rides.
Extra $50,000
While in any park, press Square, Circle, Triangle, Square, Circle, Triangle, X.
Mission completion
While in any park, press Square, Circle, Triangle, Square, Circle, Triangle, Circle. Then at the mission selection screen, press Square to complete the highlighted mission and unlock the next mission. Note: Each time Square is pressed on a highlighted mission, the rank of the completion increases (from bronze, to silver, and finally gold). To reverse your progression on a mission, press Circle at the mission selection screen to remove the highlighted mission medal.
Mini-games
Get a 100% game completion to unlock the final two mini-games.
Easy friendship
Tap X on the Chat menu instead of choosing which is the best conversation for someone.
Easy money
In Career mode, get good rides and leave the game running while you are sleeping. You should have lots of money afterwards.
Faster Romance
Play the Flirt mini-game instead of the regular conversation. Note: This option only becomes available after you reach the Love Interest level.
Keep pressing the third icon to either become their friend or sweetheart faster.
Different hat style
Change the Hat Stall theme. To do this, press Square, then choose "Inventory". Select the Hat Stall, select "Customize Style", then choose the themes. Change it with Left or Right.
Star Wars reference
When you play the Flirt mini-game and the topic is "Galaxy Far, Far Away", your character will say something similar to "In my opinion, Anakin Skywalker is the best Star Wars character ever".