The Battle Cats - Paper Skyscraper
Trying to build up money before hitting the base can be somewhat tedious, but the actual boss fight is quite easy. Spam the usual units that work well against zombies, and you'll be fine. I didn't use my Li'l Flying Cat for this run because it is very high leveled.
Mohawk +50
Manic Mohawk 30
Manic Eraser 30
Eraser +48
Cameraman 29+4
Seafarer 30
Polevaulter 30
Can Can 30+3
Bahamut 30
Jamiera +50