Spike: Um… So… Can we watch the sunrise now?
Twilight Sparkle: I doubt it. But sure, let’s go anyway.
DM: Finally. As you trot towards city hall, you notice that the starry night sky is perfectly clear thanks to Rainbow Dash’s weather management.
Rainbow Dash: Yawn.
DM: Inside, Rarity’s decorations perfectly set the mood. Ponies feast upon the food Applejack provided. A choir of birds is ready to sing at Fluttershy’s direction.
Twilight Sparkle: What about Pinkie Pie? What was her role in all of this?
Pinkie Pie: What else? To be the LIFE OF THE PARTY!
The more you think about this episode, you eventually realize that Pinkie Pie was just a force unto herself. She wasn't on the checklist for anything, but she became a prominent part of the event anyway.
Yeah she managed to gather everyone in town in one location for a party, keep them up (partying) all night, and then move them all to the another party. Then after the plot, what does she do? She throws another party.
Actually, I have seen it theorized that based on episode 1 "room full of people at a welcoming party = 'and now you have lots of friends'" and Party of One, that prior to episode 1, Pinkie was ACQUAINTANCES with everyone in town but had accidentally neglected (due to not quite grasping concepts in the same way as other people) to become FRIENDS with anyone on any sort of meaningful level. She loved everyone, but nobody really cared about her in a deep way (other than maybe the Cakes? But they are more substitute parents than peers). Ergo part of why "Party of One" went the way it did.
I could see that. A friends list a mile wide and an inch deep.
Honestly, despite how fun she is Pinkie might actually find it HARD to make real friends - what typical Ponyvillian would tolerate her randomness long enough to see the good-hearted Pony underneath?
Pinkie wasn't involved in the preparations at all, probably because they wanted a somewhat formal event and not a party.
And we all know that if Pinkie had been involved they would have got a party.
Pinkamena wasn't involved directly with getting the Summersun festival ready, as far as I can tell, but her throwing the welcoming party for Twilight may have acted as an additional catalyst to Twilight's social group. It certainly would've introduced everyone else in town to her.
Pinkie was good friends with the other four already so her personal involvement into the story is still aptly explained away. Despite not having any real role, she wasn't going to let her friends remain in a lurch.
I have to disagree. Perhaps Pinkie was friends with some of the other four, but Dash thought she was terminally lame for a while, as was pointed out in the beginning of Gryphon the Brush Off. It was only after Pinkie showed that she was into pranks that Dash really started liking her.
My take is that she is one of those people that are just always there when somethings up. Those people that are well so supernaturally well informed about who has to do what and whom they borrowed the party desks to and all that stuff.
There have to be other people out there that are like that.
Wizards of the Coast already did it back before MLP was cool.
http://www.wizards.com/default.asp?x=dnd/dd/20060401a
Somehow I think it was 'priming the pump' so to speak... as it seems the show matches pretty closely with UA variant lvl 7-9 D&D characters. Including rounds/lvl effect durations if you consider Pinkie in particular a spellcasting class. Ex. Giggle at the Ghostie matches the time ranges of an opposed 15th lvl Cone of Fear/ 7th lvl Supress Emotions. Pinkie often makes use of the 'Disguise Spell' feat.
Ah, the big villain reveal. I was once allowed to be a villain. Trial and error hour at the comic shop. Let me be a Demi-Lich so we could see the end of the campaign without the players killing me early. It was a lot of work, but the players enjoyed themselves more feeling that the dungeon master wasn't the one out to kill them. They felt that it was an actual challenge worth seeing. I also enjoyed it because I made for one hell of a villain. They never guessed that I kept my phylactery in a safety deposit box at House Kundark.