When to Attack
The best time to attack your opponent during an Ultimate X match is when he is on the cage's cables, trying to get to the X. At this point, you can hop behind him on the cables and kick him to the ground.
Defense
If you are going for the X and you see your opponent coming at you, quickly press the "Circle" button to jump from the cables, turn around, and kick him until he falls down.
No Finishers
Since the goal in an Ultimate X match is to grab the X, there is no reason to try using your finisher on your opponent. Even if you use the finisher, your opponent will automatically get back up.
Title Match
When fighting in the title match, you do not have to worry about your two opponents, Samoa Joe and Chris Daniels, going for the X. They will be busy fighting each other. This will allow you to easily grab the X division title.