Would there really be an advantage for a character who is precognitive and knows your moves ahead of time so they can prepare to counter and avoid them? They actually done something similar in Agents of Shield where one character read the minds of opponents and thus knew what moves they were thinking of.
You’re describing two very different things.
A psychic combatant that can read their opponent’s intentions could, potentially, have a significant advantage in hand-to-hand. It’s not insurmountable, and they’d probably be vulnerable to whatever your setting’s counter-psi training permits.
Of course, if your setting has psychics, it seems a little unlikely they’d need to resort to hand-to-hand if they have the ability to broadcast. Why, punch someone, when you can just overload their senses with simulated pain?
If they can’t broadcast, and it’s receive only, then it might be helpful, but that’s determined by how easy it is to process the information they’re getting. At worst, it could be a detriment, as the telepath would need to filter through more information. At best, they may be able to streamline that information in the moment, to the point that they could react before their opponent strikes. Though, the issue here is the idea that your foe will be thinking about their tactics mid fight; that’s not happening.
Hand-to-hand combat by trained fighters is extremely fast. We’ve talked about how this stuff starts running up against your brain’s ability to process information. In a fight, you’ll never think, “I’m going to hit them there, then follow up with that.” Hand-to-hand training is about revising your reflexes. No conscious thought necessary, which is good, because you don’t have time for that. This can bite someone with practical training in the ass, because they’ll respond to a perceived threat when the cause was benign. What’s a psychic going to do about this? Well, you can’t really read what your opponent is thinking, and then plan ahead in the fray.
Telepathy can help in a gunfight. The combat tempo is slower, and you have time to read their intentions and adjust your tactics accordingly. That’s not true in hand-to-hand.
In both cases, telepathy can grant a significant advantage before the fight starts, adjusting your tactics to specifically counter your foes. But, it does nothing for melee combat.
Clairvoyance, prescience, precognition, whatever you want to call it, is fundamentally different. You’re not reading their mind, you know what they’re going to do. This is, in a lot of ways, the exact opposite of telepathy, depending on how far out you can see.
Again, there’s a real risk that your oracle will be overwhelmed and distracted by the information they have. If they see too much, that’s more things they need to filter through, and it can impair them.
A character with even one second of foresight will have a huge advantage in hand-to-hand. They really will have time to see what their opponent will do, and counter it. The advantage is defensive, they know what to defend against.
It’s also possible they may have the ability to see multiple outcomes, which would make this an offensive ability, picking the most devastating attack, while leaving them less certain what their opponent will do. I’m thinking of Midnighter (from The Authority) here, but there are other examples.
It, probably, wouldn’t be viable to switch between modes mid-melee. I’m basing this on how the human brain processes information. That said, seeing the future isn’t exactly normal, so, maybe they could switch on the fly. It depends on how your setting’s superpowers work.
When you step back and look at something like ranged combat, prescience becomes far less useful. You’re not reacting to what your opponent does, you’re reacting to their tactics, and those won’t be apparent until they’re in position and executing them. Though, prescience may let your character “dodge” the occasional bullet.
There’s an edge case here where you might have a character who is borderline omniscient. Paul Atreides comes to mind. But, that’s a special case, the character is, nearly, all knowing, and can see their opponent’s plots and strategies before they’ve even devised them.
It’s also possible you have a character who does both. Star Wars‘ Jedi are an example. Technically, The Force grants them a limited degree of prescience, but this comes with a degree of extrasensory awareness that allows them to counter tactics on a slightly larger scale. That said, the same limitations also apply; they’re blind to larger plots and strategies. Anything that specifically works around, or excludes The Force tends to slip past them. It’s a reasonable limitation from a character perspective. The Force grants a very potent set of superpowers, so it makes sense that Force Users are prone to overlooking anything that doesn’t pop up on their radar.
So, yeah, this can be useful, you can make this work. But, as with a lot of power sets, it’s limited, and as a writer, you need to be aware of those limits when you’re working.