http://www.youtube.com/watch?v=CITKEZ06xIE
One of my all-time favorite videos. A Roy player beats Mango (in one match, but that's besides the point) in pools.
1:04 - The dash out of grab range to shield-poke with forward B is clever use of DED.
1:32 - dthrow to platform waveland tech-chase is ****ing brilliant. Sethlon is a god.
Note his heavy use of dtilts and dash/pivots just out of grab range to DED. Also note the specific DED combos he uses based on the situation and percent Sheik is at. Sethlon uses flare blade (neutral B) a lot in aerial combos because it has a higher knockback and more range than fair. I think it also does more damage.
Also, of all of Roy's moves, his least useful (imo) is dair. dair is really only appropriate as a short hop OOS option if the opponent is just behind you. Short hop straight up or away from the opponent and immediately down-air so that you have protection as you escape OOS. However, if the opponent is facing you and you're shielding facing away, you'll probably get grabbed as soon as you try to short hop before the dair comes out. Hence why dair is fairly useless. When it spikes, it's a meteor, so it's bunk in that department as well.
EDIT: Oh, yeah, his usmash is pretty bad, too. It has it's uses, though. Rare, but it does have at least one or two situations in which it can be considered an option. Also his usmash spike is a meteor.
http://www.youtube.com/watch?v=HA-jSSXDM2o around 2:10 in. Keep in mind Roy (and Marth) have decent knockback on their uthrows. An upthrow at 200% is a guaranteed kill on Zelda on almost any stage.