(psych up regirock + physically defensive probopass js. also braviary could Sub or Roost and somewhat stall it out, depending on what it's locked into, so it isn't the safest choice @ Gigalith, while psych up Regirock is uncommon but works well, forcing Braviary to switch or take Recoil [tho I guess Curse Regi could work too], while Probo can paralyse it if it plays well and can keep using Power Gem over and over and only 4hko's iirc? this is just for general information, though!!)
Nevertheless although it's been used before, it fits somewhat well here (it'll be nice to see a different counter from what was used before, though).
252 HP / 252 Def / 4 SpD
Scald can burn it if it tries to attack outright with Stone Edge, and can recover HP with Protect/Wish and stall out Stone Edge and force a switch, considering it does 50% maximum. Or if it Explodes after SR it's only a 2HKO and it'll survive with a little HP and Gigalith will be dead. Unless the opponent has a Gothorita or a Diglett or a Trapinch to trap it, Alomomola can switch out and regenerate HP to around half ready for its next switch in.