In terms of attack, yes, "Obelisk the Tormentor" and "The Winged Dragon of Ra" (if it has enough attack) can beat "Stardust Dragon".
However, if you are referring to the destruction effects of "Obelisk" and "Ra", then "Stardust Dragon" does "beat" them since it can negate their abilities and destroy them.
Chat with our AI personalities
if you sacrifice ra and slifer while obelisk is on the field obelisk wood have infinite attack and nothing can stop him
The card you are thinking. The fusion between "Slifer the Sky Dragon", "Winged Dragon of Ra", and "Obelisk the Tormentor" is called "The Creator of light, Horakhty".
The Winged Dragon of Ra is basically the strongest because while Obelisk and Slifer have a fixed amount of attack points, the Winged Dragon of Ra has infinite.
obelisk
obelisk the tormentor the wing dragon of ra slifer the sky dragon