ok so i beat the game without looking at to much info on battle trophies, kinda wanted to see if i could figure out them myself.. and well after 80 hours on earth mode about only 10 or so shop orders left and only the ice(water) ring left to get the last of the chests i think im doing well. weird thing is i do know edge needs to kill 30k baddies by himself so i've used him the entire time as mc, becuase i think i need to have him as mc for the enemies to count right? if not thats a huge waste...
anyways, i finally looked at the battle trophies faq and it says i should not use earth mode first... do i miss out on any batte trophies or other things??
For most of the Battle Trophies, you have to be controlling the guy you want to get the trophy for. Also keep in mind that you have to do everything in the same file -- you can't kill 15k bad guys with Edge on this cycle, and 15k in another cycle (e.g., on another difficulty), because partial progress is linked to the save file, and not to the system data file.
If you're aiming for the Platinum Trophy, starting on Earth difficulty means you have an extra cycle to complete, because you have to beat the game on Universe and Chaos to unlock trophies. Earth doesn't help you towards that, because Galaxy difficulty starts as unlocked to begin with. As far as the BTs go, I don't think it makes that much of a difference. You might even find some of the really nasty "skill-based" BTs easier on Earth mode, particularly the ones that oblige you to use certain characters to kill certain bosses (main game or post-game) within a certain timeframe. The lower enemy HP on Earth difficulty can help you out there.
You have more shop order quests left than you think -- you haven't run into the last shopkeeper yet, and he's got a whole bushel of them for you.
You'll want to keep that Battle Trophy FAQ handy, because there are a number of BTs that won't reveal themselves at all. Mostly ones involving boss battles in one form or another, but also a couple of other obscure ones that aren't particularly intuitive.