Tried to work out how to best use Silvally-Normal.
I've tried a SD sweeper set with DE, but generally even with HP investment and no Life Orb I found it just dies too quickly to accomplish much.
Scarf Silvally shouldn't be used in OU, it's a poor man's Genesect. Genesect hits much harder with U-Turn, has a stronger Explosion and STAB if it gets the Download boost (+1 Iron Head does more damage than Double Edge, has no recoil and an annoying 30% flinch chance), a bit more speed and a much better typing. The only thing Scarf Silvally really has is Parting Shot, which I don't think makes it worth using over Genesect. It might be a usable substitute for Genesect if it gets banned though.
In the end, here's what I came up with:
Silvally @ Normalium Z
252 Atk / 4 Def / 252 Spe
Adamant / Jolly Nature
- Explosion
- Crunch
- Flame Charge
- Swords Dance
This works around its lack of longevity by just focusing on nuking and booming to tear holes in the opposing team. STAB 200 BP Breakneck Blitz which may be followed by the most powerful Explosion in the game (besides boosted Explosions like Download Genesect's or Galvanize Golem-Alola's) is incredibly hard to switch into, and becomes even worse when boosted with Swords Dance. Silvally's bulk is usually enough to setup on most things provided it isn't facing strong Fighting-type or boosted attacks. Generally, you're aiming to use Flame Charge (brings Silvally up to 433 / 475 Speed) against fast teams, taking advantage of their lower bulk to smash through them (most uninvested Pokemon that don't resist Breakneck Blitz are usually in danger of being OHKO'd), or set up Swords Dance to blow holes in slower teams. In my experience so far it usually at worst forces a trade, and more often than not takes out atleast 2 Pokemon on the opposing team before biting the dust.
Some calcs:
252+ Atk Silvally Crunch vs. 0 HP / 0 Def Gengar: 234-276 (90.3 - 106.5%) -- 37.5% chance to OHKO
252+ Atk Silvally Breakneck Blitz (200 BP) vs. 0 HP / 4 Def Charizard-Mega-X: 262-310 (88.2 - 104.3%) -- 31.3% chance to OHKO
252+ Atk Silvally Breakneck Blitz (200 BP) vs. 0 HP / 4 Def Pinsir-Mega: 246-291 (90.7 - 107.3%) -- 43.8% chance to OHKO
252+ Atk Silvally Breakneck Blitz (200 BP) vs. 252 HP / 0 Def Latias: 315-372 (86.5 - 102.1%) -- 93.8% chance to OHKO after Stealth Rock
+2 252+ Atk Silvally Breakneck Blitz (200 BP) vs. 252 HP / 252+ Def Toxapex: 307-363 (100.9 - 119.4%) -- guaranteed OHKO
+2 252+ Atk Silvally Flame Charge vs. 252 HP / 0 Def Celesteela: 190-224 (47.7 - 56.2%) -- 84% chance to 2HKO
+2 252+ Atk Silvally Explosion vs. 252 HP / 4 Def Skarmory: 268-316 (80.2 - 94.6%) -- 50% chance to OHKO after Stealth Rock
+2 252+ Atk Silvally Crunch vs. 252 HP / 0 Def Aegislash: 216-256 (67 - 79.5%) -- guaranteed 2HKO
This set's biggest threats that I can see are Ghost-types and Protect moves nullifying its nukes, Terrakion (fast Fighting-type, resists everything on the set, and can take an unboosted BB/Explosion comfortably enough), physically defensive Skarmory, strong priority, fast scarfers (particularly those with Fighting coverage), and most unfortunately Mega Sableye. The various trappers can take out Ghost-types, Terrakion and Skarmory, speed control can reduce Terrakion and many scarfers to a check, and the threat of priority can be reduced with Psychic Terrain or screens. Not much can be done about Mega Sableye outside trying to bait it with a lure, or maybe having Safeguard or Mystic Terrain support to help Silvally get enough SDs to KO with Crunch before it can get burned.