If you have played inFamous 1, your Trophies will basically give you a boost in inFamous 2 but will also alter other things as well, like if you were good or bad. Here is what your Trophies will do for you in inFamous 2.
- Finished the game on any difficulty: 1,000 starting XP
- Have obtained a Good or Evil Trophy: Start with level 1 good or bad karma
- Have found 25 percent of the blast shards: Energy core (health bar segment)
- Have found 50 percent of the blast shards: Two energy cores
- Certain unspecified “decisions” also result in changes in side missions, Dead Drops and dialogue
Source, IGN