>>22268831Both can work, since Steven's Metagross is bulky enough to stand on its own most of the time - but Fake Out or Mat Block on its side doesn't hurt, either.
>>22268870Quick Claw does NOT override +1 priority. It does make the user move first in its speed bracket - the same effect as Custap Berry, i.e. not priority-increasing, just giving it the first draw in the speed-determined move order. Priority moves still move first, and negative priority moves still move last.