Well I need something which counter Xerneas checks. Deoxys can't switch in, and Scizor have priority...it is possible to use a physical deyoxys-A, I found that one (surprisingly) good move he could use was grass knot, as it usually got a OHKO on kyogre and groudon. (it is SE on both and they are extremely heavy) Deyoxys also has a decent physical movepool with a few fire moves to kill steel threats
also, victini's STABs are supereffective vs BOTH of Xerneas' weaknesses and has a fairly decent movepool, including the most powerful non-sacrificial move in the game
Victini is viable as a Scarfer maybe, but not much more...
Ho-oh sounds like a very good partner to me. Ho-oh can even use Defog to get rid of Sticky Web for Xerneas.