so far, it seems like it would go this way:
-Strelok, being more sneaky than tidus, manages to land a few shots with one of his firearms.
-Tidus would most likely be using his ultimate weapon, which is linked to his health. While he's at full health, he's an absolute powerhouse, but as he gets injured, he gets a lot weaker.
-At this point, Tidus has taken heavy damage, but he knows where Strelok is (but he is out of sword range). Tidus tries to hide behind the nearest tree.
-While under cover, Tidus casts haste on himself. Strelok will either reload, throw a grenade, or both, depending on his weapon, how fast he is, and how long it takes Tidus to cast haste.
-Tidus would then either try to cast cheer, buffing him up, or move out from cover. If he tries to cast cheer, that would probably be enough time for the grenade to go off and kill/incapacitate him.
-If Tidus moves out, he would not really be able to charge directly at Strelok - Running in a straight line towards someone with a gun makes you a good target. Instead, he would try to flit from cover to cover.
-Strelok would most likely try to get him as he moves between cover, but I imagine he would be lucky if he got any good shots.
-If Tidus were to try to case slow on Strelok, it would most likely need him to stop long enough for Strelok to be able to get a lot of shots in
-Once he gets behind close enough cover, strelok would most likely switch to using a shotgun. Tidus would almost certainly have switched to a different weapon at some point.
-At this point, it becomes a question of whether a wounded, hasted Tidus can kill Strelok in close quarters.
In summary, it doesn't look good for Tidus.