Stepping on the red tiles in the pyramid won't activate for me, furthermore when I attempt to reset positions the game freezes up no matter what I press, but I can still soft reset the game.
Bold of you to ask to trade of all things.
If you haven't already, please look at this cool Item Guide and press Ctrl+F to look up where you can get a Fire Stone, cause they're also for sale in shops.
Meowstic Crest: +15 Sp.Def/Def, Increases turn duration for Light Screen/Reflect
Chandelure Crest: +10 Speed, Increases STAB effectiveness
Slurpuff Crest: Grants Harvest Ability (I feel kind of iffy about this depending on its usefulness but it'd be fun.)
Vanilluxe Crest: +20 Speed
I believe you can find them growing somewhere in Terajuma, but the best way would have to be growing them from the Occa Berry that was given to you. I personally recommend using the Unreal Time mod in the Modpack due to the 1 second = 1 minute in game if you're also doing some pretty long grinds to maximize on watering the plants.
Edit: Forgot to mention just in case they haven't gotten the Wailmer Pail I'm linking the Item Guide.
By stones it's only one stone, one was a Heracrossite and the other I forgot that you could choose from during a side quest. But yeah, get them just in case or something.
EDIT: fuk mi waddledee got to mi