Copied from Fluster Zero on TA:
This achievement can be fun, but for many will turn in to a painful boosting session. To get this you need get 1000 or more battle points with EVERY character online.
You cannot rank up in Tag Team or Endless Battle mode. To do this it will take being able to tolerate a grind of boosting, casual gaming, and in some cases mad skill.
Basically to get ONE character to C it takes 20 wins, no losses. To boost this it will take about 40-50 minutes to boost 1 character up from D to C. The way I'm doing it takes that long at least because I am doing all the super/ultra finishes achievements on the way. The matches will go by faster if you do the same once you get the 365 flashy background finishes trophy.
There will be for 35 characters a total of 700 matches you must win without losing one. Average a minute twenty seconds a match lets say with loading times and the actual match, It will take you ROUGHLY 14 hours to do this for one person. That isn't likely that you will fly through it that quick as well unless you have all the best moves lodged back in your head so lets just go with 15 hours to be safe. From there you have to help your boosting partner :) so there goes another 15 hours roughly.
So think before attempting this one, make sure you really want to grind ANOTHER game for 50 points.
TIME: Roughly 15 hours for 1 person
MATCHES NEEDED: 700 wins
BORING LEVEL: 9/10
TROPHIES YOU CAN GET WHILE GOING FOR THIS: all the 50, 100 attack type trophies and the 365 flashy background finishes along with all outfits, taunts once you're done.