Charizard?
Rock Slide?
It is immune to EQ, Resists Sacred Fire, is faster, cannot be burned and can carry Rock Slide... Thunderbolt is a problem, but if it comes in on Roost, Sacred Fire, or EQ, it should be fine.
If you feel it will still hit Charizard hard even when resisting Fire attacks, that is fine, just strap on Salac Berry and watch Blaze and Salac Berry activate on the Sacred Fire switch-in, as Charizard kills with Rock Slide next turn.
P.S. With people now discussing Solrock and Lunatone as possible OU with Sandstream support, does anyone think they could be counters?
Solrock has 95 Base Attack and STAB on Rock Slide, with 85 Defense and a resistance to Fire and an Immunity to Earthquake, and its low Special Defense can be boosted with Sandstream (taking Thunderbolts).
Lunatone has 95 Special Attack (not worrying about halving its Attack stat from Burn, although HO-oh has awsome Special Defense), and 85 Special Defense (further boosted by Sandstream). It resists Ho-oh's STAB too, and can use Hypnosis or HP Rock with STAB, or even Light Screen, Calm Mind, etc.
Also Rest+Talk Shuckle and Cradily with Toxic+Rest could be awsome counters with their nuetrality and Sandstorm Special Defense boosts. STAB Rock Slide on Cradily doesn't hurt either.
Lets also not forget about Regirock, as it can use Rest to heal off EQ and burns, while posing as a massive Defense tank with necessary STAB Rock moves.