For reference, I will formally post the set I was thinking of for Agility Sawk:
Sawk (M) @ Life Orb
Trait: Sturdy
EVs: 4 HP/252 Atk/252 Spe
Nature: Adamant
-Agility
-Close Combat
-Ice Punch/Thunderpunch
-Stone Edge/Earthquake
Sawk outspeeds most, if not all CS Pokemon after an Agility boost, and the Base 125 Attack makes that even more terrifying.
What if Simisage received Sap Sipper?
This would be interesting with Simisage's coverage options, giving it another welcome toy. Simisage is now immune to Sleep Powder, Stun Spore, and Spore, and now Giga Drain, Leaf Storm, Leaf Blade, etc. all give it a free attack boost. Here is one set:
Simisage (M) @ Salac Berry
Trait: Sap Sipper
EVs: 252 Atk/4 Def/252 Spe
Nature: Jolly/Adamant
-Substitute
-Seed Bomb
-Rock Slide
-Brick Break/Acrobatics
This hits pretty hard at +1 Attack, and can easily get +1 Speed on an opponent that it outspeeds (most of unboosted NU). The EVs maximize attacking power and speed while requiring only 3 Substitutes to get into Salac range. Seed Bomb is Simisage's STAB of choice since it didn't get Leaf Blade or Wood Hammer (Torterra laughs). Rock Slide covers four of Simisage's five weaknesses, and has a flinch chance. Brick Break gets excellent coverage with the other two moves, and most importantly, lets Simisage hit Steel-types such as Lairon very hard, especially at +1. Alternatively, Acrobatics hits Fighting-types such as Sawk very hard after getting into Salac range (at +1 Simisage outspeeds Scarf Sawk too), as well as giving Simisage an edge over its competitor, RP Torterra.
If this were to come to reality one day, I see one core being a possibility. The first part will be Simisage with the set above, and here is the other piece:
Seismitoad (F) @ Life Orb/Damp Rock
Trait: Swift Swim
EVs: 4 HP/252 SpA/252 Spe
Nature: Modest
-Rain Dance
-Hydro Pump
-Earth Power
-Sludge Wave/Focus Blast
Seismitoad synergizes very well with Simisage, with no common type weaknesses between them. Seismitoad is a great, bulky sweeper under Rain, blasting past the Steel-types that wall Simisage, while taking away its Fire weakness. Between these two Pokemon, much of NU is hit super-effectively, and a +2 Seismitoad and +1 Simisage will be outspending almost everything else in sight. The powerful dual STABs are a welcome gift.
*A third member, such as SD Beartic, LO Ampharos, or Skuntank could be added to this core as well with the needed coverage moves.
However, despite Simisage's new potential as a cleaner, if you want brute physical power from a Grass-type, you are probably still better off with SD Sawsbuck or RP Torterra.