In order to purchase every positive Karma upgrade for each power, you need:
1.) To have this trophy
2.) Quite a bit of XP (which you can get from missions, side missions, blast shards, random enemies, etc etc)
3.) To complete all 15 "Good" Side Missions
Upgrades that are neutral (gray in color) do not count towards this trophy, only the upgrades that are in blue.
Questions, corrections and neg vote justifications below.