*deep breath* Ok... You're picking a really hard costume, but I'll see what I can do.
Shorts/Suspenders: I'd suggest using black plether. You can buy it here. www.stretchworld.com
For the Jecht symbol on his right leg you'll have to use fabric paint or acrylics but it should look nice on the plether. It looks like he's got some webbing on the back of that leg attatched to the front with eyelets, which are easy to buy and put on. For the webbing, just use the plether in overlapping strips.
Shirt: I'd just use white cotton for the lining and either yellow cotton or quilted fabric for the outside. Same goes for the blue, and red plether or vinyl should work for the webbing on his left arm.
Gauntlet: This one's a little tougher. On his left arm he's got this armored gauntlet-type thing, looks like layered metal from the pic I'm looking at. If you want to go all-out you could make it with sheetmetal, or go the fiberglass resin way. There are ways to do it with fabric also, if you don't want to work with either of those options, but you'd really just have to play around with stuffing and/or padding. Personally I'd make it out of fiberglass, but it's kinda dangerous and not a lot of people like working with it.
Accesories: Gloves should be pretty easy to come by, as well as the belt and chain he has hanging from his waist. The little crosses on the suspenders could be made any manner of ways, and I've seen the necklace on sale at various anime stores and on Ebay.
Good luck, hope some of this helped you!