Reindeer: Kill ten players in a single game, not over a cumulative period of time.
Cactus: Kill 20 players in a single game. This one is much tougher to get than the previous one.
Wolf Puppy: Kill 30 players in a single game.
Polar Bear: Stay for a total of 5 seconds outside of your area. This one is very easy to do.
Gingerbread Man: This one requires you to stay for a total of 10 seconds outside of your area. This is cumulative, not in one game.
Pirate Ship: Stay 15 seconds outside of your area cumulatively. Not in a row, and not all in one game.
Seal: Knock off two players in a row, without being knocked off. An easy way to do this is wait until they come into your space, stick around inside your space, and cut them when they enter your area.
Penguin: Knock out three players in a row, without anybody knocking you off. Same strategy as above.
Little Bird (that looks like a chibi Pidgey): Revive with the ad-based “extra life” revival a total of five times.
Unicorn: Do the same as above except revive a total of ten times and not five.
Vulture: Revive a total of 50 times by watching the ads after you get knocked out.
Double Decker London Bus: Kill off a total of 50 players.
UFO: Kill a total of 100 players. Once again, this is not all in one game, this is cumulatively.
Red Highlighter: Kill a total of 1,000 players. This one takes forever to get.
Meat with a bone in it: Cover a total of 500%. Not in one game, that would obviously be impossible, but over time.
Ghost: Cover a total of 5,000%.
Lava Demon: Unlock a total of 5 planets.
Hot Air Balloon: Unlock a total of 10 planets.