Here is how The Element of Heroism chose Flash Sentry in The Tale of The SquarePants Master Ship Builders.
On the S.S. Headliner.
Titanic: (sighs as she look at the picture of herself with Olympic, Titannic II and Britannic)
SpongeBob SquarePants: Hi, Princess Titanic!
Titanic: Oh, SpongeBob. I didn't see you come in. Is there anything you want to talk about?
SpongeBob SquarePants: Just wondering how you became an Alicorn.
Titanic: It was a long time ago when I was the RMS Titanic.
SpongeBob SquarePants: Really?
Titanic: Yes.
In the flashback after the RMS Titanic sunk.
Titanic: (narrating) Years ago, After I sunk into the Pacific Ocean for a very long time. Until, She came... Princess Celestia. She used her magic and created a soul inside of me and resurrected me into an Alicorn and I was proclaimed Princess of Equestria.
Back in present.
SpongeBob SquarePants: Wow.
Titanic: And that is the whole story.
Voice: ICEBERG AHEAD!!!
SpongeBob and Titanic looked at the crow's nest with José Carioca up top.
José Carioca: We're about to crash into Iceberg!
Mickey Mouse: YEAP!
Goofy: GAWRSH!
Donald Duck: OH NO!!!
Oswald the Lucky Rabbit: Hard to starboard! Hard to starboard!
The S.S. Headliner's steering wheel reverse and sails closed in.
Gremlin Gus: Let's hope it's stop in time!
Britannic: Brace yourselves!
The S.S. Headliner stopped just in time.
Pete: Phew! That was a close one!
Titanic: Is everyone and everypony alright?
P.J.: We're okay!
Pete: No broken bones!
Max Goof: We're good.
Goofy: I'm okay.
Flash Sentry: What does the map say, SpongeBob?
SpongeBob SquarePants: It says here, (points at the map) One of the Elements of Harmony is somewhere around the Iceberg.
Captain Stubbs: Not to worry, SpongeBob. We'll find it. Pongolo Pete, You search around the sky with Rainbow Dash.
Pongolo Pete: Aye Aye, Captain! Ready, Rainbow?
Rainbow Dash: Ready, Pongolo Pete!
Pongolo Pete: Then, Let's go!
Plankton: Come on.
It took a while as the whole crew searched and searched, Until....
Pongolo Pete: Hey, Look! there's something glowing inside that iceberg!
Rainbow Dash: It could be one of the new elements of harmony!
Plankton: Let's check it out!
Mr. Krabs: That's so beautiful.
Merlock: Surprise! (turns back into his true form)
Gremlin Gus: Prescott!
Gremlin Prescott: Long time no see!
Mickey Mouse: And Merlock and Dijon!
Flash Sentry: We gotta stop them!
SpongeBob SquarePants: (notice the glow) Guys! Look! The Element is Glowing!
Flash Sentry: (notice the element coming to him) What's happening? (felt it's power blasted Merlock, Dijon and Prescott away)
Merlock: Whoa!
Dijon and Prescott: NOOOOOOOOOOOOOOO!!!!!!!
Gremlin Gus: SpongeBob, What kind of Element is this!?
SpongeBob SquarePants: (looked up in the book) It's the Element of Heroism and it's chosen you, Flash!
Flash Sentry: Me?
Twilight Sparkle: Only someone like you would be Equestria's greatest heroes like us heroines!
Flash Sentry: (his cheeks turned red)
Mr. Pym: Let's go!
SpongeBob SquarePants: Right, Mr. Pym! (reads the map) Set a course to The Pride Lands!
And so, The S.S. Headliner continues to sail.