This achievement can done in conjunction with the following achievements:
Hey!-Hit with 100 Neo Max Super Special Moves
Heheh, Not Bad!-perform 50 Max Cancels.
Best done on Versus Mode, 1v1 match. Two controllers required.
After selecting your character and a dummy character, you'll be given 5 Levels to choose from that will alter settings in the match.
For Player 1, select Level 5 P HD Max so you start with full Hyperdrive gauge and 5 meter stocks.
For Player 2, select Level 1 HP 50% so your opponent starts with half his normal vitality.
Once the match starts, hit your opponent a few times so his health is around 33% or less, guaranteeing you a KO with the Neo Max Special.
There are two methods to using Neo Max Super Special Moves:
Normal Neo Max Super Special Move:
Requires a full meter on the HyperDrive gauge and 3 stocks of Super Meter. If you chose Level 5 P HD Max, you'll start fully charged up and ready to go.
HyperDrive Mode Neo Max Super Special Move:
Requires 2 stocks of Super Meter while your character is in HyperDrive Mode. Activate HyperDrive Mode by pressing LK and HP at the same time when your HD gauge is full.
Please see my solution for the Heheh, Not Bad! achievement if you'd like to see a character specific example of a Neo Max Super Special Move using Terry, and how you can work towards the 3 Neo Max SSM achievements.
Otherwise, simply pause the game and view the command list for character specific NMSSMs.
1vs1 is the fastest method, as you'll have to do some meter building after the 1st round Neo Max SSM if you do 3vs3.
If you follow the Heheh, Not Bad! Solution, you can knock off this achievement and the 50 MAX cancels at the same time, when they're completed, simply do 50 more Neo Max Super Specials using the same setup to get the Hey! achievement.