List of enemies

Enemies
These are what the zombies are for: to fight enemies. The enemies have levels ranging from easy to super hard. The easiest enemies are the ones in Old Mcdonnel, and the hardest are those in the Zombie vs. Aliens. Even though some enemies are very hard, the zombies still have a significant advantage that they could fight together unlike the enemies who have to fight one by one. However, most enemies from pirates and above are stronger and tougher than combined zombies.

Old Mcdonnel and his flimsy farmhands
Old Mcdonnel should not be really a threat to you. He is really easy and can be beaten by 8 regular green zombies. From the start, he throws things at a relatively fast rate. However, after level 10, his throwing speed become 4 times and it is recommended to use blue zombies to make sure that you won't lose any zombie. The destructiveness of the objects are also quite high: 5 shots can kill a garden zombie WHOLE. Its brain drop rate starts as excellent, goes down when it approaches level 9, goes up until level 13, then drops down as your level increases.

Corporateville lawyers
The lawyers seem pretty tough and hard to fight against but their power is just about the same as the flimsy farmhands of OldMcdonnel. However, they are nothing compared to the combined zombies and the pirates. His throwing rate is slow, at a rate of 1 item every 5 seconds. I would recommend an army of 2 tough, 6 large, 6 girl, and 2 fertilizer zombies. His brain drop rate starts high at the start but goes down as your level increases.

Dread Pirate Arrnold and his band o' scallywags
If you think that this enemy is really hard to beat, you are correct. Although there are only 6 of them here, the scallywags are about 5-20 times as powerful as the lawyers and nearly twice as tough. However, one of them is easy to beat, just like a lawyer. When the boss comes down, make sure that the front zombies are the slow ones, because if the front zombie is fast, then the boss will be fast. Every about 5 hits, he would instant kill a zombie, so give him some time to recharge by putting a slow zombie at the front. His brain drop rate is pretty high but drops as the level increases.

Mr. Whiskers and the ninjas
From this level, red zombies and below are essentially useless. These enemies are not as strong as the scallywags are their total health are more than twice the total of the pirates. The boss, Mr. Whiskers, summon carrots to block zombies from reaching the enemies. Just tap 20 times to shrink it. All I can say is to use combined zombies, however mutations are not really necessary, but can assure you of no zombie losses.

The Robots in the Factory
This invasion has only 3 enemies, and none of them is really a boss. They take turns being the boss and they are all in boss-level difficulty, like Mr. Whiskers. Different bosses summon different objects like the junk wall, which you have to tap several times to shrink it. Now, at this level, mutant combined and master zombies are needed to assure no zombie losses

Aliens
This is the hardest invasion and probably the last invasion the Zombie Farm game. Although the aliens are pretty weak, their total health amounts to 1450, which is much more than the others. 'No matter what your zombies are, it is almost impossible to assure you no zombie losses as you will usually end up at do or die. The boss summons laser shots that weaken and eventually kill your zombies.