Sombra as Sinestro Corp- One of the most feared villains in Equestria, gave the entire Crystal Empire PTSD just by ruling them for a short time.

Trixie and Indigo Tribe- Having to atone for her misdeeds in the past.

Chrysalis as a Red Lantern- Fuelled by her rage born out of her desire for revenge against the Mane 5

Sunset Shimmer as Red Lantern- (this was done before Equestria Girls actually came out) Rage born out of a desire for revenge against Celestia for rejecting her.

Fluttershy as Blue Lantern- One of the mosre optimistic members of the team, always hoping that things will turn out for the better.

Windigo as Sinestro Corp- A creature greatly feared by Equestria for what they did in the past. Thing is Red Lanterns are much more specific than just being rage-filled. They're fuelled by a rage born out of a desire for revenge against someone. Atrocitus wanted revenge against the Manhunters for massacring his people, Bleez wants revenge against the Sinestro Corp for gang-raping her and destroying her wings, Dex Starr wants revenge against the people who murdered his owner, etc.