Nicknames!

[Braver]

Squall: Moody

Selphie: Little Miss Annoying

Rinoa: Doggy Woman

Zell: Hothead

Seifer: Mr. Arrogant

Irvine: The Gunner

Quistis: The Whip

Edea: Magic On Ice

Doomtrain: Rolling Thunder

hehehehehe

[Jiro]

Zell is obviously Chicken Wuss :monster:

[nik0tine]

Rinoa: Doggy Woman

[Tigmafuzz]

Odin: Odin

This is easier than I thought.

[Cloudane]

Squall: Whoever...
Selphie: LocoCoco
Rinoa: Brick dumb as
Zell: Chicken Wuss
Seifer: Tosspot
Irvine: Twogun don't ask what his second one is, he might show you *shuddder*
Quistis: Miss Whippy
Edea: OooooooMatron in the voice of Kenneth Williams
Laguna: Goofball
Kiros: Edward as in scissorhands
Ward: Jack as in lumbering..
Biggs & Wedge: Dumb & Dumber
Raijin: Noah , ya know?
Fujin: FOGHORN
Cid: Robin Williams
Nida: Wotsisname
Ellone: Princess slightly sarcastically

[Tigmafuzz]

Ellone: Princess slightly sarcastically

FPxY8lpYAUM

[Red Mage Coffman]

My list looks a little something like this...

Squall: Emo Git

Selphie: Loli

Quistis: Teacher Gone Wild ;)

Rinoa: Brick. Cause that WAS amazing. Or Cardboard.

Zell: Chicken Wuss.

Irvine: I'M A COWBOY. ON A STEEL HORSE I RIDE... Or pussie.

Laguna: The man with the machine gun. Or a Bad Dream...

Kiros: Girly Man.

Ward: Idiot. Anyone who uses an anchor in combat must be mental.

Edea: Queen Cleavage

Cid: Robin Williams.

[Mercen-X]

Squa: Black
Rinoa: Blue
Quistis: SPANK ME!
Selphie: Eyetweak
Zell: Tyson will sue you!
Sorceress Edea: Lady pillows

[Jiro]

Let me try this for serious then:

Squall: He's called Leader several times in the game, but there's clearly a lot of potential for the nickname Lion to be attached to him. Another animal nickname, Wolf, could work too, with his personality attempting to be a loner.

Zell: Aside from Chicken Wuss, he could also get Hot Dog for his fascination with them, Fist because of his fighting style, or Trick thanks to his acrobatic skills.

Selphie: Selphie is a little bit harder as her personality doesn't lend itself to any obvious nicknames. Genki (as in, Genki Girl) at a stretch, but it's not really a good nickname. Something could be drawn from her position on Garden Committee, her position as the Ragnarok pilot, or even some kind of Import or Newbie nickname due to her status as a transfer from Trabia.

Quistis: Instructor works obviously as she served as a teacher. Possibly some kind of similarity to be drawn through her use of a whip, but I can't think of any terms. She's the, what, Card Club Ace so that works as well.

Rinoa: Angel based on her limit and her pup. Owl because Timber Owls. Witch if you want a somewhat insulting name based on her becoming a sorceress. And, of course, the nickname she already has: Princess.

Irvine: There are a fuckload of sniper related ones, including Sniper itself. Deadeye, Headshot, Hunter, Hitman, etc. Cowboy works too.

Laguna, Kiros and Ward have a lot of options too but I cba to do them yet.