Where are numbers 264 - 267?

264 is Regirock, who is found in Vien Forest Cave, you need to use the Buizel river. To expose him, you need level 5 Crush, for example, a Garchomp.

265 is Regise, who you can find I Almia Castle, in the room with the Mismagius. To get to him, you need level 5 Burn, for example a Magmortar.

266 is Registeel, who you can find in Chroma Ruins, in the hall bear the Shadow Crystal room. To expose, Level 5 Cut is needed, for example, a Gallade.

267 is Regigigas, where you can find in Hippowdon Temple, in the second part with moving tiles. The sand in the room's center will have a whirlpool. Enter to go to secret room to find three pedistals. You MUST Have Regice, Regirock, AND Registeel to enter Regigigas's room.

Hope I Helped.

#264- Regirock: Vein Forest Cave; you will need Surf x1, and Crush x5. Two Pokemon legible are Buizel, and Garchomp.

#265- Regice: Almia Castle; room with Mismagius. You will need Burn x5. Pokemon legible is Magmortar.

#266- Registeel: Chroma Ruins; Shadow Crystal room. Use Cut x5 to expose Registeel. Pokemon legible is Gallade.

#267- Regigigas: Only available for capture when all 266 others have been captured. Hippowdon Temple; room with the moving tiles. You MUST have Regice, Regirock, and Registeel with you to enter Regigigas' room.

Good luck!
Hope I helped,
Sk8rboy