Originally posted by Mobstercrew
You will miss 1 trophy (Unlock Classic Mode) Level 10 its 1-2 hrs from new game.
You can get all the story and weapon upgrade trophies before this one if you join online games or don't string together any high value KO combos to level up your turtles to level 10. Multi kill trophies can be done in the dojo outside the main game as well. Plus, you can put these saves on a USB and transfer them if you want to get each turtle's max weapon upgrade trophy even quicker. It'd be pretty hard to get anything OOO or be flagged unless your first trophies were for completing all challenges or surving wave 20 in arcade. Both are gold and require a completion of story mode to unlock.
EDIT: Speaking of transferring from a USB, you can upgrade Don's genius ability for 3 quick weapon points, and max a turtle's weapon. Do it 4 times and you'll have all the max weapon trophies. Beat any level and you'll receive additional weapon points. The trophy guide suggests replaying chapter 1 five times, but if you have a USB, I'd go this route instead. You can't skip cutscenes, and it's pretty boring.