Wandering Around the Lake: The Search for Mesprit

After the fiasco with Team Galactic at Spear Pillar, you may choose to return here, and if you do, you will see that there is now a cave in the middle of the Lake. If you access to HM 03 Surf, you will be able to access the cave and thus meet the wondrous Emotion Pokémon, Mesprit. When you enter the cave, it will notice you and fly down to see what is going on, saying its name as a greeting. What you choose to do next is totally up to you. You may choose to battle with the Mesprit, but under no circumstances is this Mesprit able to be caught.

You must have access to HM 03 Surf before you attempt this challenge. Depending on how you handle this situation, Mesprit may choose to allow one of your Pokémon to learn Fire Blast. If you wish to take on this challenge, say so in the post you make when entering the Lake.