Flame Stag's attacks are as follows.
1) Speed Burner (X-Buster style)
2) Upwards flame toss
3) Fire Dash (Chargeable)
He also has his rising attack which is performed by jumping immediately after a crouch. It can be connected into a downwards attack.
As for in-air attacks, he has one double fire toss, similar to the 2nd ground attack.
One more thing, his gameplay differs slightly when in his boss room. His wall jump is more accurate to the original game in the sense that he flies upwards as opposed to just jumping off which is how I have him regularly. He also flies higher up during his rising attack.
P.S.
The boss stage was originally created by UHMEEEEBA of Trinity MUGEN. I simply edited the stage to fit this game's ratio and such.