Nintendogs+Cats quick money! No Competitions.

#1. You can go for a walk and weave through traffic cones with touching them and receive presents that you could exchange for money.

#2. Also while you're on a walk you can meet some people that you've streetpassed with...sometimes they will give you, accessories, food, treats, and toys.

#3. You can go on pedometer and either really walk or shake the 3ds, either way you will receive gifts. 

#4. Don't sell piggy banks, crash 'em

#5. Last, but not least, sell any toys that your dog does not like playing with