(spoilers)
Another good episode, and with an excellent lesson too.
The new sport of Buckball comes to Ponyville, and Applejack and Rainbow Dash immediately get to work building a team, which requires one of each type of pony. After some practice with Pinkie Pie and Fluttershy to find a unicorn for the team (with virtually all volunteers being completely pathetic), the members selected for the team are all surprises: Pinkie Pie, Fluttershy, and Snails.
And with an upcoming game, Applejack and Rainbow Dash attempt to train the team as hard as possible, but the effort backfires and leave Pinkie and Fluttershy thrown off their game. Facing too much pressure, Pinkie and Fluttershy quit the team (with a bit of interesting role reversal between the two at that moment too).
Thankfully, Applejack and Rainbow Dash soon realize the mistake they made, and come up with an interesting way to fix everything. They claim to be willing to fill-in for Pinkie and Fluttershy, but are in need of practice, so they play against each other just for fun. At the end of practice, Pinkie and Fluttershy are doing great again, and are then asked if they could take back their places in the team. As for the remaining issue of how to deal with the pressure, it's Snails who offers a solution: "Just don't think about it." And in the end, it all works out great for the Ponyville team.
The message of this episode was a pretty good one. Some people thrive when under pressure, while others do better when they're just having fun, so don't expect the same strategy to work for every team.
(end spoilers)