Quick cash:
To do this trick you'll need a lure rod and a few lures, any type will do. Go to the menu and equip both the lure rod and a lure onto Max. Now press R1 to switch over to Monica. Pick the same lure you put on the lure rod and keep equiping it in Monica's menu screen. It will begin to stock up on Max's screen. You can equip up to 999 lures for free, and then sell them for tons of loot.

All costumes in new game:
Start off by playing through a game collecting new costumes for Max and Monica. Now when you begin a new game, and your in the new game menu to choose a beginning costume, you can start off with any costumes you had collected from a previous game.

Name Change Ticket trick:
Cash in medals you collect through Mayor Need for Name Change Tickets. Now pick the name of any weapon in Max and Monica's arsenol and type it in exactly how it's spelled. It's case sensitive so remember to uppercase the beginning of words onto the ticket.
For example: Question Shooter
You will now have that weapon, but it will only have base stats. Powered by Coranto