This is question most do when planning a sweeper. I have the answer.
1st:ATTACK POWER. With attacking moves you want damage right? So, attack power is obviously a factor.
2nd:ACCURRACY. You want to HIT with power, so accurracy counts too.
3rd:CRITICAL HIT RATIO. For most moves it's 1/16(6.25%), but for some it's 6/16(37.5).
4th:ADDED EFFECTS. You know: paralysis, flinch, etc.
5th:STAB. self explainig.
Then you do this formula to measure all these factors in a single one.
This will find the average damage given by the attacks:
STAB=same type attack bonus(if applied 1.5 if not 1)
acc.=accurracy in decimals(example:0.70 for thunder)
CHR=critical hit ratio(17 if standard, 22 if high)
Let's do this with the popular physical attacking move earthquake being used by Tyranitar=
Got to a number, 106
And what if this same Tyranitar used Rock Slide?
So, this Tyranitar would be better using Rock Slide than Earthquake because of STAB.
You ask: and the added effects?
Then it becomes like this
Rock Slide=~107.58+1/3 flinch, meaning it has a 1/3 chance of flinching the foe
And here I have listed the average damage of some of the most used attacks nowadays separated by type:
Signal Beam=79.69+1/10 confusion
Silver Wind=63.75+1/10 raising all stats
Crunch=85+1/10 lowering SD
Faint Attack=63.75+ never misses
Thunder=89.25+1/3 paralyze (yeah, better than dragon claw and crunch)
Brick Break=79.69+ breaks reflect
Cross Chop=110 (!!!)
Blaze Kick=105.19+1/10 burn (!!!)
Fire Blast=108.38+1/10 burn
Overheat=148.75+ SA harshly fells +1/10 burn
Fire punch=79.69+1/10 burn
Aerial Ace=63.75+ never misses
Shadow Ball=85+1/5 lowering SD
Giga Drain=63.75+ absorbs half the damage inflicted
Ice Beam=100.94+1/10 freeze
Ice Punch=79.69+1/10 freeze
Sludge Bomb=95.63+1/10 poison
Rock Slide=71.79+1/3 flinch
Ancientpower=63.75+ raising all stats
Psychic=95.63+1/10 lowering SD
Metal Claw=50.47+1/10 raising ATK
Meteor Mash=90.31+1/5 raising ATK (better than thunder and blizzard)
Iron Tail=79.69+1/3 lowering DEF (better than both metal claw and steel wing)
Hydro Pump=102 (really interesting, lol)
HIDDEN POWER=74.38(better than many other moves)