Rock fall vs Rock sling

I'm hunting for a boulder, but in the mean time...

Which one is better? rock fall vs rock sling?
Power wise it seems that the rock fall does more damage, dunno why the rock sling is there? One stuns and the other reduces speed?

What do you recommend?

i prefer rock fall.... coz tend to stun opponent...

Rock fall is power 60, 95% hit rate, possibly stuns.
Rock sling is power 50, hit 95%, chance of speed debuff, and possibly stuns.
Sling seems to decrease speed a decent amount of times, I find neither one stuns much as I would like. Rock sling just looks cool as hell!

The speed debuff isnt enough to get your Blocky to go first, even with boots on,(If there are working). Im not sure if the debuff stacks, but im going to try and test it.

They have equal chance of stunning. Rock Sling has a high chance of lowering the speed of the enemy, this is usually enough to get first attack.

Their powers are so close together that you will usually not be in a position where 2 Rock Falls will kill but 1 Rock Fall and 1 Rock Sling wont.

So start with Rock Sling, maybe lower speed enough to get Rock Fall off next turn thereby only taking 1 hit instead of two.

Rock Sling also adds the second offensive Earth move on some of the Earth monsters since 10 PP on 1 move isnt enough to get through many maps.

What if you want to stay with one of them?
Is it really worth it those 10 attack points in the rock fall?
For example, if I can kill something with 2 rock falls, maybe I will need 3 rock slings or something...
And the speed debuff is not that much so is like it wont matter at the end.
btw, I'm going to use it in a behe so I want to put sand storm and remove one of those.. and leaving the first slot empty to learn kamikaze... someday in the future when it hits 40 lvl

Well Ill be straight with you, I used an Armordillo for my earth monster when going through the Canyon, with a B rating in SPD and now level 39 it still only 53 SPD. Back when it was lvl 35 and just got Rock Sling (and I dont know what SPD stat) it would attack first on the second turn if the speed debuff triggered and I wasn't Paralyzed. And that is against Electric monsters, arguably the fastest element.

The speed lowering is fairly significant and getting hit 1 less time is a big deal.

That said, its six of one and half a dozen of another. Both skills have 10 PP and 95% hit and a chance of stunning, Rock Fall will do a better job gettin' it done, but Rock Sling will help you take less damage, and the cost of possibly 1 extra turn.

But remember, with those 3 Rock Sling turns you are probably only going to get hit twice, so that extra turn will probably only cost you an extra PP, not extra health.

@Ryeballs thanks for your input...

My Blocky at lvl 42 has a B+ stat of 58 speed, After the debuff it still goes 2nd against elect mobs in canyon Vet/exp modes. Normal mode it usually kills em 1st shot or so close i use Bodyslam next.