Pokémon scarlet Catching Groudon

To start, fly to Alfornada and walk west of the Pokemon Center to reach the entrance of Alfornada Caverns --this is where Groudon resides.



Follow the path into the cave; once you see the first trainer, walk to the right until you're almost to the edge of the cliff and use your Koraidon/Miraidon mount to fly over to the cliff at the opposite end, to the east.
Once you have made it over, walk to the southeast corner of the rocky terrain, where Groudon is standing menacingly.





Groudon is in Alfornada Cave.

The best way to find it is to enter the cave from Alfornada

then head towards the giant glowing Tera Umbreon, since the Groudon is on the cliff next to it