Easy "FIREth Of July" Trophy
On map Deathspin. Go to the bottom right dead-end area, and keep the town and knight tower destroyed while collecting powerups. This is your "safe" area for the map ("safe" being relative to the enemies that are spawning). Your main goal is to destroy royal carriages and allow knights to rescue them. You can destroy them across the level boundaries, and ransom princesses nearby if you run low on health. Once you get 12, the achievement will pop up.
Easy "Lightweight" Trophy
At Princess Rush level and attempt to get 15 princesses within 4 minutes and 35 seconds. You can steal princesses the AI dragon ransoms while protecting them on your own to help speed this process up. Sometimes there's a little luck involved getting gold in Princess Rush games due to AI patterns and spawn luck, but with enough persistence the achievement will eventually be yours.
Easy "Pacifist" Trophy
On the Mound map With two other co-op partners, have the person designated to get the Pacifist achievement to take Speed and Carry upgrades, while the other dragons take Speed and Fire upgrades. Every dragon should get at least 2-3 upgrades in Defense in order to not get one shot, as losing the multiplier will hurt your overall score. The general strategy is to let the players not getting Pacifist to destroy bomb wagons, knights and castles, farmer carts, etc and to allow the Pacifist dragon to pick up as much treasure and deposit as possible.
Halfway through when wizard towers start spawning, any dragon can pick up the gem to take back to the hoard, but the fire-breathing dragons are best because the gem will max out the Pacifist's carry burden that could be used for more treasure. When giants start spawning, they have to be number one priority for the team, as they drop a lot of treasure. As long as thieves don't steal gold from you, and no one gets hurt and loses the multiplier, getting the Gold rating for Pacifist on this map is easy and reliable.
Easy "FIREth Of July" Trophy...