Here is the full list of all 14 Megaton Rainfall trophies - there are 13 bronze and 1 gold.
Beat the game
Acquire every superpower
Get every trophy
Beat the game in hard mode
Beat the game in less than two hours
Finish one mission with no casualties
Finish 3 missions with no casualties
Get rank A in one mission
Get rank A in all the missions
Destroy 3 enemies with a single Gigaton Blast
Destroy Earth
Kill yourself
Collect every Xenosphere
Get really far from Earth