First episode, Pinkie accidentally spills a potion on some cookies, and after she leaves for a moment, Twilight arrives after an argument with Owlowicious and eats one cookie and forces Applejack to eat another, resulting in them being sucked into the potion bottle. Pinkie returns and quickly figures out what happened, so she rushes over to Potion Nova for help rescuing them. Potion Nova quickly mixes up an antidote and pours it into the potion bottle, but while Applejack escapes, Twilight remains trapped inside. Potion Nova explains the only reason the antidote could fail is if Twilight wanted to stay inside the bottle, so Applejack eats another potion-tainted cookie to return to Twilight and convince her that she can't stay hidden away forever and should instead confront her issues. Twilight eventually accepts and the two of them successfully escape the potion bottle.
Second episode, Twilight is very eager to begin learning potion-making from Potion Nova, but is also very worried about potentially messing something up. She tries to hide her anxieties from Potion Nova, but fails miserably. Potion Nova assures Twilight to not worry too much, and suggests channeling her emotions into the potion-making, with surprisingly remarkable results.
Third episode, Pinkie finds herself alone at Sugarcube Corner, missing her friends who are all out doing other things. She's so bored and desperate for companionship that when she finds Twilight's duplicator device (seen before in an earlier episode a few weeks back), she comes up with the idea to combine a drawing of her friends, some cookies, and a potion, and forcing all of that through the duplicator, resulting in five cookies shaped and decorated just like the drawings. Pinkie wants those special cookies to stay with her and do all kinds of pretend activities, but astonishingly, the cookies come to life with a desire to go out and explore the world. Pinkie tries to resist at first, but eventually allows the living cookies to leave. Thankfully, Pinkie's real friends soon return, bringing an end to her loneliness.
Fourth episode, Pinkie wants to host a "tech conference" style meeting with potential investors for Sugarcube Corner. Her friends are concerned it might not work for her, but they allow her to make preparations. Once she's about to get out on stage, her nerves get the best of her, but her friends are there to support her, no matter what happens. She goes out and presents cupcakes as the latest thing worth investing in, but once her speech is over, she discovers there was literally no one in the audience, aside from a few of her friends.
The first pair of episodes seem to continue the Potion Nova arc, with Twilight freaking out about things, as usual. The second pair of episodes were more focused on Pinkie, but while I found the second of those to be just complete nonsense, I actually liked the one with the living cookies, purely for the humor behind it all. Overall, pretty much the usual mix of episodes we've come to expect from this show.