Both of them are proficient H2H fighters and swordsmen. The problem for Slade is Deadpool's unpredictability. Deadpool has a good variety of weapons and some very unorthodox ways of using them. Deathstroke has the superior physical prowess but he's going to approach this fight logically and efficiently and that won't work against Wade. I think Deadpool would win by some insane strategy like using grenades at point blank range.
Boba Fett has a wide array of superior weaponry and he's not going to hesitate to use it. If they start 100 yards apart as the battle rules state, I don't see how Slade can get to him faster than he could pull a blaster out and shoot him through his good eye.
There's been a lot of talk about Canary being trained by the best, but it's worth pointing out that being trained by the best does not in any way make you the best. Natural talent plays a bigger role in those who are masters of their skill set.
Taking guitar lessons from Eddie Van Halen doesn't mean you can play guitar like Eddie Van Halen. Nor did Eddie Van Halen get to be such a great player by taking lessons from someone else who was better.
So then is it fair to say that Black Canary a better H2H fighter than Moon Knight because she trained with Batman? Nope. Not even close.
Moon Knight has a natural ability to kick tail and take damage. That's what it would take to beat BC.
And at the risk of repeating myself and others, Black Canary does not start a fight with her scream especially not on a normal human. Since MK has the ability to physically overpower her and is a naturally proficient fighter my guess is still that he takes the narrow victory because he takes her out before she utilizes her scream to its full potential. Khonshu will be pleased.
Definitely understand why many are leaning towards Canary, but I'm not convinced she'll feel the need to use the scream until it's too late.
I think Moon Knight is a beast and an efficient fighter, so he's going to put her down fast. Canary doesn't routinely begin her assault with her scream and I don't think she's out to liquify people's brain's especially if she knows they're normal humans. Likewise if she did hit him with the scream don't count out Khonshu stepping in to help Marc soak the sonic blast and give him a boost of strength and speed to punch her in the throat.
I think Marc makes her eat truncheon and then takes her down before she ever considers letting loose the scream. MK for a narrow win 6 out of 10.