This achievement can be done in Practice Mode. I believe supermoves count as special moves as well, so you'll unlock 'Superhuman' at the same time. If you don't think you'll be overwhelmed, you can go for 'Feel the Burn!' at the same time as well.
Go to practice mode and choose a character. Work your way through each character in order, to help keep track.
Once in game, go to PRACTICE OPTIONS and set METER GAIN to REFILL. Next, go to MOVES LIST and scroll over to SPECIAL MOVES to view all the special moves for the character. Up to 6 moves can be tagged using the Y button so that they show up on screen for easy reference.
Back out of the menu and start performing each of the moves you've tagged. Once you've done this, go back to the special moves list, clear your tags, tag whatever special moves are left and perform those as well. Finish off with their supermove.
Be thorough. Do each special multiple times if you're not sure you did it right. Once you've made it through every character, the achievement will unlock when you exit practice mode.If it didn’t unlock for you, these are the things that are easily missed to check for first:
This seems to be the thing people miss the most the first time through. Every character power counts as a special move, even power-up ones like Superman and Bane’s, even though you might assume they wouldn’t count.
Raven’s Demon Stance:
Her demon stance character power has a very limited amount of time before you go back to normal. Keep an eye on this while performing her demon stance specials, and wait for it to recharge after it runs out.
Hawkgirl Wing Evade and Soaring Hawk follow-ups:
There are 3 different follow-up attacks to Hawkgirl’s Wing Evade and Soaring Hawk moves that are listed in the description, but not in the special moves list. Press the corresponding button after doing the move to use the follow-ups.
Green Arrow’s arrows:
His character power has 3 different types of arrows. Activate and fire each type.
Ares’ Weapons Of War:
Ares’ character power is a series of sword and axe moves. Do each at least once.
Harley Quinn’s Bag-O-Tricks:
Her character power has 3 possible items. A photo frame, a flower, and dynamite. Use her character power until you’ve seen all 3 at least once.
She leans back during high feline evade, and does a little hop for low feline evade. Also be sure to do her 5 scratch version of her Cat Scratch power. Scratches are earned by scoring hits. Hit your opponent with other moves until you see MAX at the bottom of the screen. Press to unleash the full attack.
If you think there's something you may have overlooked, or not sure if you're doing a move right, here is a series of videos for every special move, meter burn, and super:http://www.youtube.com/playlist?list=PLSvi5kfsxQY0XTpcSVKs_v...