Alright, lucky for you, you were the most recent post in this board, and the title interested me.
Your biggest problem? Dialogue.
They approached the door, being careful not to make any noise. "We're almost in, Sumi". Whispered the one gripping the door knob.
Firstly, if you wish to label the speaker after the dialogue, it should use a comma. And that comma goes
inside the quotation marks. Which would make "whispering" lowercase.
"Good, we'll have it soon enough." Whispered Sumi in response. "Good, are you ready? Once we go in there, there's no going back". Warned the other one. "I'm ready, Tennon".
Except for the first bit of dialogue here (which should end with a comma anyways), your periods and commas are still in the wrong places. And when you have a new speaker, you always give them their own paragraphs. Think of it this way: your characters do not like sharing paragraphs, and you want your characters to each be important to the story somehow. Not giving them their own paragraphs is insulting them. So here, you would give Tennon his own paragraph starting with his dialogue. After "the other one," who would start a new paragraph.
[...]entire time.They quietly walked towards the towering
buidling in front of them; guided only by the dim moonlight.
I'm assuming these were typos, but you need a space after that first period and you had a random new line. "Buidling" is "building."
One of your "slowly"s has two "l"s. Your "click" should be italicized, not in stars. I would even suggest giving it its own paragraph, as well as any other onomatopoeia word. "Atleast" is two words, and with the words inside the dashes, there should be spaces seperating the text and dashes. Don't put a comma directly after that last dash, it doesn't need to be there.
The semicolon between "first" and "had" isn't necessary. When you're giving the red rectangles their name, just say, "called Pokedexes."
You mispelled one of the "pedetals" here. "Thefar," (and I'm praying this was a typo) should be two words. "Thrid" is "third," right? The semicolon between "pedestal" and "sat" should just be a comma.
When you're adding a bit to a sentence and have to set it off, it's either by semicolons or commas. If it has a coordinating conjuction at the beginning, it should be a comma. If there is no coordinating conjuction, it should be a semicolon. More on commas and semicolons here:
http://owl.english.purdue.edu/handouts/grammar/g_commacomp.html
So that semicolon between "it" and "but?" That should be a comma. And if he is going to pick it up in a few seconds after flipping through it, add something like "but he didn't just yet."
Overall, it was an interesting prologue. Mysterious and had me interested enough ^^
Really, though, where are you typing up your chapters? I worry you're not using Word and have no spellcheck to immediately work with. If you have no word processor with spellcheck, go get OpenOffice or use an online spellcheck. You have plenty of typos.
(And, also, as a personal preference, could you keep the font unedited? It makes you look like you're trying too hard to make an impact on readers, and that you need to enlarge text just to make your chapters look better. You can do that by properly spacing your dialogue out.)