I've combined this statement with "Corki" and "Mid Lane"; which resulted in sheer disappointment. No Summoner Spell beats Flash, with a few exceptions such as Shaco, Nasus, and other bruisers in certain situations in which Ghost has proven to be superior.

It is. The cooldown on W is massive and it can get interrupted quite easily.

Flash is not mandatory. Corki has Valkyrie to escape, and if you get Maw of Malmortius and Zhonyas, you shouldn't have a problem with surviving.
On the other hand, Corki is very slow has does not use normal ADC items, like Phantom Dancer or Statikk Shiv, so he ends up VERRRY SLOW, even with trinity force. Ghost can help outrun Volibear, Master Yi, or any other insanely fast champion. Save Valkyrie to get over walls, and if it's on cooldown, go into Zhonyas until it is off cooldown. Check my hybrid guide for a more detailed explanation.

I like old guides. Don't flame for being old. Just means the creator is more experienced in the game. I personally used Guardian Angel until I found out Zhonyas is just much better on Corki's new AP/AD scaling.
Check out my hybrid Corki build.

yah i made this in season 2 but now im reworking it for it to fit season 4 lol, sorry for the misconception.

This guide is heavily outdated. The guy is talking about Surge and promotion within the guide which don't exist anymore since S2 or something? :O

Flash is a mandatory summoner spell and your cheat sheet doesn't show Masteries. For Runes you should use Armor or Health Seals and Magic Resist Glyphs into many matchups. You mention Summoner Spells that don't even exist anymore and I think you put way to much colors and unnecessarily Corki's (put it under spoilers at least).