Originally Posted by Fat Mr.lol
Psystrike / Grass Knot / Fire Blast was also pretty good coverage when I used it. Unlike Ice Beam, Grass Knot lets you take down Tyranitar at +1 with a little bit of residual damage. The only problem is Heatran, Dialga in rain, Lugia in rain (maybe neutral weather, +1 Fire Blast hurts extremely hard in sun), Specially Defensive Giratina and Jirachi in rain but against the first two, its not like you could defeat them with Ice Beam anyway, and Aura Sphere > Fire Blast solves issues against Heatran and Dialga. Specially Defensive Giratina-a will phaze you out regardless of what you run. I can't say anything about Lugia though. Latios and Latias take massive damage from +1 Psystrike, it 2HKOes, but its not like Ice Beam OHKOed so...
The problem for this is, what is Grass knot going to hit? Kyogre is already get destroyed by Psystrike, and ice beam kills Groudon just like GK. I suppose you can hit Water Arceus and Rock Arceus (and hit Ground Arceus stronger) with it, but ice beam allow you to OHKO Garchomp and Rayquazza, hit Giratina-a AND O, Lugia, Dragon Arceus, and Flying Arceus stronger. I think ice beam>GK