Scorched slab:
In fortree city go to where you would battle gabby and ty you will see water which is blocked by kecleon battle kecleon and you will see a big rock there is a door go through and you will see a platform with a item.

Sealed chamber:
This is tricky to find it is in the middle of the ocean current on route134 it is a small diving area if you find it go down and follow the path you will see braille it says go up here.so dive again and you are in the sealed chamber take a pokemon that knows the move dig got to the back of the sealed chamber and it says dig here.dig and there is a surprise behind there my aron doesn't know dig anymore so i don't know what the surprise is so try and find the chamber and find out for yourself.