To earn this, from the main menu go to challenges, then survival and select "EXTREME" difficulty option. You will pick your fighter and face 100 straight one round matches, with some random option to heal or buff your attack/defense between matches.
Luckily now this trophy is much easier, as you are now able to save your progress, quit the game, back up your save files on the cloud or USB stick, and then continue. Whenever you lose a match, quit the game, download the save and try again from your last "checkpoint".
There is also a continue feature now, but it seems it is only available to Champion Edition owners, and costs 800 fight money per, so I didn't use it. I'd prefer saving that for characters.
There are "Battle Items" that you can use along with the perks you pick from a randomized list. I think this is also new, but I only used on the very last match, so I was 100% health and very overpowered.
What you do is play a few matches, at the end of a match you press
and save.
I saved roughly at 20th, 40th, 50th, 60th, 70th, 80th, 85th, 90th, 95th and 98th matches. But this is of course entirely up to you, and your tolerance for losing progress after defeat versus tolerance for enduring the long loading/startup times every time you close the game to backup the save.
As for strategy, my first recommendation would be to use whatever character you are more comfortable with, and abuse the save backups, but if you want to follow what I did, I used Guile and mostly his 1st V-Skill with slow sonic boom, ocasionally roundhouses, flash kicks and throws. No fancy combos at all. AI seems to be programmed to not jump in on a crouching Guile. See the video for an example of how my last two matches went, they are very representative of the whole run.
It was relatively easy, I had to reload my save only 3 times, but every match or rather every interaction with the AI is a roll of the dice.
I'll try to paint a picture.... Every time you throw a hadouken the AI will, 30% of the time, take it straight to the face, 50% block, 15% jump over and hit you once, and 5% will jump over with inhuman frame perfect precision and land a devastating combo. You get 2 or 3 bad rolls in a match and it is game over. So my advice is to save, even if you are winning easily.