Hm, having all three of Focus Blast, Stone Edge and Hydro Pump consistently hit sounds like it could be pretty nice. Especially since Focus Blast and Stone Edge are pretty much the worst attacks in OU. I'll look into my moveslots and see if I find room for it, definitely an interesting idea though.
I should probably mention that gravity only lasts for 5 turns. While it is zero trouble for lando-I to set it up for himself on a forced swap (phenomenal tactic as it counters darn near every air balloon mon ever), ttar will only be able to take advantage of it very situationally (basically, he has to swap into something that threatens lando like a bulky knock off user or an ice type attack) while keldeo pretty much only gets to use it when he revenges for lando, so take that into account when making your decisions.







