There are theoretical arguments that a _massless_ spin-2 particle has to be a graviton.  The basic idea is that massless particles have to couple to conserved currents, and the only available one is the stress-energy tensor (**the stress-energy tensor is not the only tensor which could couple to a spin-2 particle, the electromegnetic field tensor also could couple and photons are yet massless**), which is the source for gravity.  See this [answer][1] for more detail.

However, the particle discovered at LHC this year has a mass of 125 GeV, so none of these arguments apply.  It would be a great surprise if this particle did not have spin 0.  But it is theoretically possible.  One can get massive spin 2 particles as bound states, or in theories with infinite towers of higher spin particles.

[1]: http://physics.stackexchange.com/questions/14932/why-do-we-not-have-spin-greater-than-2