>>20607016Sigilyph is pretty much the best Pokemon in Random Battles short of Ubers, because the only way to really deal with it is by phasing or using a fast Dark special attacker. Which aren't common in Randbats.
Its usual set is Cosmic Power/Roost/Psycho Shift/Stored Power. It holds a Flame Orb and has Magic Guard. Flame Orb triggers the burn, it shifts that onto your mon (so no physical attackers), and then it starts boosting and Roosting. If you let it get to about +3 you might as well forfeit.