This can be done in Practice Mode and most characters can get their respective 10-hit combos with just the X-Ray moves (L2+R2). Some will require making a short combo in conjunction with the X-Ray, while others will rely on combo knowledge entirely.
DLC characters do not need to be done to attain this trophy.
Here's a video by PowerPyx that will list the characters 10-hit combos. Make sure you use the same variant as the video describes as some variants will not have the same combos available in one versus the others.