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Easy mode is bullshit. Let's assume only the enemy remembers anything, and has no limits to his power.
Consider the revelation. Somehow, you learn that your enemy reverses time. Maybe his goon brags about it, or your friend has a heroic sacrifice involving a clock tower.
AT THAT MOMENT...you gamble whether this is the first time around, it the Xth time around. Consider if an alternate version of you may have botched the elimination of this enemy and given him a chance to reset., and his ability to reset goes back long enough that your enemy gets to plan differently.
If it's not the first time around, you're dealing with someone who 1. Survived the plan an identical copy of you thought was best and 2. Knows that you are going to try and eliminate them. Let's say kill them. Your enemy is going to be just as ruthless as you to save his life, and presumably can run a few Groundhog days to gain virtual days of time to travel around and acquire information about you, your habits, your patterns, your capabilities. Who knows how many times he's gone toe to toe only to slip away after gaining vital information?
Your only move, then, is to defy yourself. You have to try to introduce as much complexity, ambiguity, and unintuitive strategies. You can't just think outside the box, you have to think outside your own head. You have to hope he gets too cocky with his godlike foreknowledge and you trap him in a black swan situation.
The downside...trying this esoteric strategy will be really dumb if this is the first time around, and you might have gotten the job done if you just out a bullet in his head instead of crashing a double decker bus into him. In which case, you sow the seeds for your own potential downfall, breaking the element of surprise.
So, which is more likely, that this is the Xth time, or that this is the first time? For one thing, he couldn't stop you from finding out about his power, which would be his uttermost win condition. Are you ready to gamble?