The following algorithm is how to calculate damage:
Damage = ((((2 Level / 5 + 2) AttackStat AttackPower / DefenseStat) / 50) + 2) STAB Weakness/Resistance RandomNumber / 100
So, I will just make up certain things:
Level: 100
Sp. Attack Stat: 170 (slightly larger base stat)
Base Power: 150
Sp. Defense Stat (Scyther): 60 (slightly lower base stat)
STAB: 1.5
Weakness/Resistance: 1.5
RandomNumber: 100
So, the formula BECOMES...
Damage = ((((2 100 / 5 + 2) 170 150 / 60) / 50) + 2) 1.5 1.5 100 / 100
Damage = (((42 170 150 / 60) / 50) + 2) 1.5 1.5 100/100
Damage = ((17,850 / 50) + 2) 1.5 1.5 100 / 100
Damage = (357 + 2) 1.5 1. 5 100/100
Damage = 359 1.5 1.5 100/100
Damage = 538.5 1.5 100/100
Damage = 807.75 * 100/100
Damage = 8,0775 / 100
Damage = 807.75
Damage = ~808
Metal Sound halves Scyther's defense, therefore doubling the power to 1616. Forest Curse also gives it another 1.5 weakness thing, making it 2424.
Until you actually give exact things, then that's roughly the answer. :3
TL;DR: The answer is roughly 2424 damge.
Hope I helped. :)
Source: Serebii