How to win against bigger level
1.buy a 2 - 3 ninjas
2.level the first ninja until black belt & upgrade the weapon shop to buy more weapons
3.do it at the second ninja
4.then the 3rd ninja
5.If you have 3 full level up,upgrade the blimp
6.buy more ninjas
7.keep doing the 2nd to 6th steps
8.enjoy

So Claire Taylor just gave the worst tip ever. Don't do what she did at all. Do not get a second ninja until your first ninja is a full power level 50 black belt. One full power black belt will beat 10 various belted ninjas easily. One ninja with a lot of power is way stronger than multiple ninjas with spread out power. Do not, I repeat do not buy a second ninja until your first ninja is fully levelled up. You have been warned. A black belt will destroy with no contest let's say a purple belt and a red belt or a brown belt and a red belt or even two brown belts. So make sure you understand how much weaker you are if you buy multiple ninjas and spread out your karma leveling them each up.

1. You should pick out a ninja you like the most and make that your main and level him/her up more than the rest. 2. You should have a second favorite character to level up close to the main's level. 3. You should just focus on a few of your favorites and then later level up the others. 4. You don't need more than 12. I have 12, but honestly i focus on 10. Around half are above lower blue belt. 5. You should be careful with your karma points, because you will need them for a lot of stuff. 6. Enjoy!