You don't have hazard control, at all. You could tweak Landorus to have either Defog or Stealth Rock. Brick Break seems pointless. If it's to break screens, Defog does that. Besides, unless you remove rocks on your side, Greninja's focus sash is wasted.
Then comes your other problem: your team is vulnerable to Magnezone! With three steel types that can barely touch it, it will T-bolt and HP Fire its way through half your team once the two ground type are dealt with (see below).
Having both Garchomp and Landorus being weak to ice beam makes you an easy target for anything fast with ice beam, but that can be dealt with by a steel switchin, which you don't have a shortage of, so you have that going for you
There's also a lack of explosive power to your team, which relies on setting up. Both Garchomp and Scizor need to set up before they can deal heavy damage, and that leaves only two Pokemon capable of hitting hard and fast. To remedy this, Greninja/Landorus can opt for a z move, which makes them immediately way more threatening.
That's what I think, anyway. Actual testing might prove it's more effective than it looks on paper.
