To easily win any battle, spend your daily bonus on constitution point buy(medic shop). Even people at battle arena, using special moves, cant kill you(at least with one hit).
The easiest way to get 50000 points badge is to buy glider, press up down up(while in sky), but hold up button. Monket must be alive. You will be flying in air, because of boss you wont fall down(full group upgrade to stay alive longer). Earn 10000-15000 points, do all sky tricks and land.
 "Death Vegas"){kind=icon}
 "Caesary"){kind=icon}
 "Homerun In Berzerk Land: Berzerk Ball"){kind=icon}
 "Balance Balls 2"){kind=icon}
 "Sushi Cat"){kind=icon}
 "Async Racing"){kind=icon}
 "Globetrotter XL"){kind=icon}
 "Momentum Missile Mayhem 2"){kind=icon}
 "Dream World"){kind=icon}
 "Shopping Cart Hero 2"){kind=icon}
 "DarkOrbit"){kind=icon}
 "Spewer"){kind=icon}
 "More Bloons"){kind=icon}
 "Walkinator"){kind=icon}
 "Doodle Defender"){kind=icon}