>>44414142Roar of Time sends a loud roar back in time to when the target Pokemon was just a baby and traumatizes it for life. Hearing the roar again at the same time in the present catches it off-guard so Dialga can shoot a generic beam at it, which is extra powerful because the opponent is off-guard.
Spacial Rend tears open a portal in space to shoot a generic beam at the target Pokemon from the inside. Critical hits land more easily because the opponent is getting fucking attacked from the inside.
Both of these moves fuck with the natural order of time and space, and fairies, which are nature spirits, naturally restore nature to its correct state against warped draconic sorcery.