Now for some moves that Roy can use:
http://www.youtube.com/watch?v=ei0V5QVuSfI
0:04
This should his forward smash. It is a bit like Marth's but with a slower startup (but it's quite damaging). He holds his sword in the air and brings it down to burn his opponents. When charging, he holds the sword in the air.
0:37
His new counter attack (the down B move). Roy still does the same stance he did in Melee but this time, he makes a weak horizontal slash which sends the opponent two feet away. All of sudden they are hit with an explosion (which has just as much knockback as Link's bombs).
1:08
This could be his tilt forward. Roy simply lunges his sword forward which pushes the opponent forward.
http://www.youtube.com/watch?v=DZRILUDgcHA
0:39
Roy's possible B move. Let's take Black Knight's projectile and make it fiery. It's pretty weak (like Falco's laser) but it is fast. Don't expect any KO power.
http://www.youtube.com/watch?v=_RbyIpX30ps&feature=related
Roy's dash attack. It's like his tilt forward but less friction.
Hopefully this was a good start.
What I have noticed:
Roy is quite agile in his games compared to Marth and Ike. He's almost like Prince Leaf of FE4 and FE5 but he is not in class of Navarre, Ayra, and the other swordmasters.