I used Knit fabric for the hood and the top. What I did was cut out all the top pieces out first in the burgundy knit fabric. I used a sweatshirt pattern -perhaps even a pj top pattern to do this. For example the pattern below.
I added the cuffs to the wrists myself but here is a tutorial from Whipstitch to help you out.
Before putting the whole top together I needed those patches of black in it so I eyeballed it. I cut out pieces of black knit and fused it on the arms with fusible web. Link on how to do that here.
Is is also called heat bond and you can buy it at any craft store, Joann's and even Walmart.
Sorry I don't have that costume anymore so I can't check but I might have sewn it on in a few areas.
As for the hood , I used a costume pattern to make it out of and eyeballed the pattern on that. It's just making sure it fits , black knit around the eyes(heatbond) and making sure your child can see. It took many tries to make sure it fit right.
Simplicity has a free pattern here for you to download and you can redo it for your Deadpool hood.
Ideas for the belt and harness
On Deviant Art by Jin-Saotome-check it out here
You can buy the template(pattern)from The Foam Cave here
As for the back harness double cross sword holder , I just sewed up some pockets to hold the swords and then sewed webbing to it. No pictures for it but this is how the back looked like. You can see that he has the straps around his shoulders.
If your looking for a more detailed way to make a Deadpool costume I would check in on the Cosplay chat rooms.
You could also use this Captain America pattern from Simplicity to make the Deadpool outfit.
Or buy a it through Simplicity here