Good try but that is not the answer!

Feel free to throw other guesses out there!

Goatbrush's entry was looking lonely so I made one, but it took a lot longer to finish this than I thought it would. I put 36 references in, some more obvious than others.

The Pops of Culture

Once upon a time, there was a Browncoat who was called Mal. Having been born a Super Transformer they were able to transform into anything. This skill was used poorly by some and used well by others who coexisted with Mal in the mighty land of Oz.

Across the land, high over the Peaks of Mount Doom and just past the Overlook Hotel lived a group of sparkly vampires who were jealous of those born with tvs and computers. For this reason Mal, being a particularly avid user of entertainment, was often sent a dead parrot in the mail as a sign of Spam.

The latest shipment of deceased parrots had been particularly bereft of life and Mal could not take it any longer. Calling upon a close group of friends, warriors and Spartans, including Samus of K-2L the Powerful, Yoda of Dagobah the Wise and Paul of Caladan the Courageous preparations soon began. Gathering a number of key items including a hammer forged by the dwarven blacksmiths: Eitri, Brok and Buri, a handful of Blue Sky crystal meth and a sackful of Tribbles they were finally ready.

This mighty group of travellers faced many hardships on their way to Raccoon City. They had to defeat the Daleks and smite the Skaven. They had to collect a set number of Pokemon for an old professor. They grinded Murlocs till the sun came down. They had explored the dungeons of Dredmor and collected the Cloak of Invisibility. By the time they had reached the gates of Madness their pockets were brimming with gold, experience and Double dollars.

The final battle was about to begin. By using Gatekeeper arrows dipped in Relmyna's tears they had managed to pass the gates. A number of Zerglings appeared, at least 4,815,162,342 of them, and a major brawl started. Mal vanquished a large number of foes using their towel and the magical Knights of the Round they had collected on their journey. Mal's most formidable ally and lover, Samus, had been surrounded by Rachni. At the last moment Yoda used The Necronomicon and the tides of battle were turned. Only the citadel of Time remained.

In the citadel, the mighty Lavos awaited our hero’s party. All Paul muttered was "Who ya gonna call?” and the battle was underway. The battle was long and arduous. Many Stimpaks were used and many opportunities for one-liners were missed. By a pure stroke of luck Mal was able to hit Lavos in the core, its fabled weak spot, causing a massive eruption of light and noise.

Tired and out of mana our heroes went back to Oz where they ordered a large quantity of Martinis, shaken not stirred. They sang songs of Ice and Fire and the people rejoiced. Our heroes had become the Fresh Princes and Princess of Bel Air!

Don't mind if I join in on the fun...

The Rams of Ram

Once upon a time, there was a ram who was called Ram. Having been born a ram, they were able to ram. This skill was rammed by some and rammed by others who coexisted with Ram in the mighty land of rams.

Across the land, high over the ram-pastures and just past the ram-parts lived a group of rams who were jealous of those born with superior ramming abilities. For this reason, Ram, being a particularly rambunctious user of his superior ramming ability, was often sent formal letters of complaint in the mail as a sign of rampant outrage.

The latest shipment of ramen had been particularly ramcid (sp?) and Ram could not take it any longer. Calling upon a close group of friends, warriors and rams, including Rambert of Ramton, the rambler, Ramirez of Rambeau Field, the master of ramming things, and Ram-Leela of the Ramada Inn, the one who was not technically a ram, preparations soon began. Gathering a number of key items including a ramrod forged by the black-ram-smith, a handful of ramen and a sackful of ramson (also known as buckram), they were finally ready.

This mighty group of travellers faced many hardships on their way to Ramstein. They had to defeat the rampaging coyote and smite the legendary Ram-dingo. They had to collect a set number of ramekins for an old rambouillet. They grinded rammishly till the sun came down. They had explored the dungeons of Pyram and collected the Horn of Rambercules. By the time they had reached the gates of Ramstein, their pockets were brimming with gold, experience and tungsten (also known as wolfram).

The final battle was about to begin. By using their trusty battering ram, they had managed to pass the gates. A number of rams appeared, at least pictograms of them, and a major brawl started. Ram vanquished a large number of foes using their ramming speed and the magical Horn of Rambercules they had collected on their journey. Ram's most formidable ally and lover, Ewe, had been surrounded by deadly brambles. At the last moment, Ram used his superior ramming ability and the tides of battle were turned. Only the citadel of Al-Rama-Lama-Din-G'dong remained.

In the citadel, the mighty Rama awaited our hero’s party. All Rama muttered was "Ram" and the battle was underway. The battle was long and arduous. Many ramrods were used and many rams were missed. By a pure stroke of luck, Ram was able to hit Rama in the ramnuts, its fabled weak spot, causing a massive eruption of light and ram juice.

Tired and ramshackled, our heroes went back to the land of rams where they ordered a large quantityy of ramen. They sang songs of ram-iniscence and the people rejoiced. Our heroes had become the rams of Ram!

Great entries for challenge 4 everyone! I'll wait for maybe 3 more until judging them all.

As for challenge 5, don't give up! You are in the right direction.

In the story's template, there is one field already filled:
"For this reason [hero], being a particularly ..."
Maybe this is another hint for challenge 5.

Furthermore there's a typo near the end of the text:
"... ordered a large quantityy of ..."
Maybe just a typo, but maybe a new letter for the secret.

After some thinking and digging I'd go with Youmuu's Ghostblade.

Minor prize alert! Congratulations on figuring out half the Secret of MPCS1!

What would you like to win?

Also what was the thought process there?

Nicely done.

The quote at the beginning of the OP had led me to League of Legends (spoken by Veigar), but I'm completely unfamiliar with it. Good luck with the next step!

Oh it's not over yet. That's only half the challenge.

So now you have the words Youmuu's Ghostblade but what do you do with them?

I'd suggest going to the very start to find the answer. But to the start of what?

The secret will also reveal the theme of MPCS2...

Hmm, if you're looking for a hero, might that be Master Yi?

"Going to the very start" could mean the origin of the ghostblade, which seems to be some Touhou girl from a SHMUP called Perfect Cherry Blossom.

Or it could mean you're supposed to look at the starting letters of the challenge titles or crossword clues or story paragraphs. I can't make sense of them, personally, but I'd briefly messed with uuumoy before dismissing it as incorrect. So I reckon you're more likely to recognize a reference!

Looking further towards League of Legends will lead you no where. Maybe the secret lies elsewhere.

I also clarified my clues a bit.

Yep, I've thought about this too. It might also be Youmu Konpaku, but I just wanted to give Master Yi a shot first.
I wonder if MPCS2 is manga themed.

MPCS2 is not manga themed.

One of the words in those quotes are the right direction.