All Men Are Perverts: Case and Point: Bombs Away, Mr. 5's reincarnation, whose wings immediately shot up once he found out that Bonbon, the reincarnation of his old partner Ms. Valentine, is a filly fooler and in a relationship with Lyra. Then there's Hollow Air, the reincarnation of Absalom. That alone should speak for itself.
All of the Other Reindeer: Many Devil's Reincarnations are treated this way, which isn't much different from how devil fruit eaters are treated in the Blues.
An Ice Person: Glacier, the leader of the Fruit Brigade. He is Aokiji's reincarnation.
Brainwashed and Crazy: Fluttershy is dosed with Liquid Discord, a drug that turns her into her Discorded self for a bit, allowing the Devil's Alliance to unleash their plans.
Brick Joke: The Time Turner gags eventually end up with the pony himself showing up in chapter 26 to deliver a Big Damn Heroes moment, saving the heroes when they end up outmatched and surrounded.
Cessation of Existence: The reason Luna created Devil's Reincarnations was to prevent this from happening to the souls of Devil Fruit users, whose souls existed in a void, and would fade entirely in 100 years.
Dirty Old Ghost: Brook, of course. However, it's only when he's around human women.
Sanji as well. No matter how old he was when he died, he's been dead for a while, long enough to be considered one. Note that when he met Princess Luna, he began to cry because he thought she'd look like something else.
The Dreaded: Fire Stone, who (as you can guess) is Akainu's reincarnation. He still has the strength he had from his previous life, which (unfortunately) came alongside his ideals. He used to be on the Fruit Brigade, and he (ironically enough) was competing with Glacier, Aokiji's reincarnation, for the Brigadier position. Celestia (unsurprisingly) liked Glacier more, so Fire Stone tried to gain her favor by bringing in the Devil's reincarnation of an infamous pirate who hadn't got the chance to register yet. However, it ended up with him nearly killing Twilight and Spitfire, just because they were both infamous pirates in their past lives, and the fact that Celestia didn't care about said past lives, and as an end result Fire Stone was kicked off the Fruit Brigade and became the only Devil's Reincarnation under watch. The moment he escaped surveillance, everyone in the Brigade freaked out, and the only people who could bring him back in can't do so without causing massive property damage and loss of life.
Golden Delicious has become this for the Devil's Alliance, due to being Smoker's reincarnation. They clearly remember how dangerous he was, being the only marine to have ever been close to catching Luffy. Both Steel and Aurora freaked out once they realized it was him. The others who know his name also know how dangerous he is, but are also surprised he didn't join the Fruit Brigade and instead became a farmer.
For Great Justice: Akainu's reincarnation only differs from his past life in the fact that he is a pony and is persecuting other reincarnations for being pirates in their past life, regardless of whatever they currently are in this life.
Foreshadowing: In chapter 16, Aurora and Steel are seen having attempted to recruit Buggy's reincarnation, who's said to be a fraud after the "Ursa Minor" incident... Next chapter, it's revealed to be Trixie.
Bluebell's intro mirrors Boa Hancock's, as a way to show who she is the reincarnation of.
Gender Bender: Many male Devil Fruit bearers are genderbent when reborn due to there being more mares than stallions born in Equestria. The reason Blueblood created the Bluebell illusion is because he's the first recorded case of a female being reborn as a stallion. He does get picked on for it, with everypony thinking he's an Okama at first, but in the end they don't really care and understand his predicament.
Half Identical Twin: Blueblood and Bluebell; they even have the same cutie mark. Since they're the same pony.
Heroic BSOD: Spitfire has a minor one in chapter 8, worried about how Pinkie will see her as she is Ace's reincarnation. She's worried about what Pinkie will think of her. Rainbow Dash cheers her up.
Blueblood had a similar one when the secret of Bluebell was revealed.
Implied with Golden Delicious, Smoker's reincarnation. Instead of joining the Fruit Brigade like his past life suggested he would do, he instead became a farmer. Though he doesn't mind lending a hand when Blueblood and Applejack ask for help, and moves to Ponyville under the pretense of helping with the orchard.
Nurse Redhart, Law's reincarnation.
Ironic Hell: Nami got sent to one; it is revealed to be that she has unlimited money... and nowhere to spend it. However, she manages to evade the hell part due to giving money to Sanji to buy her stuff in heaven.
Kill It with Fire: The advice given for beating the zomponies... name-dropped. Unfortunately, the Devil's Alliance thought of that, and fireproofed the zomponies.
Obstructive Bureaucrat: Blueblood since he is put in charge of keeping things calm. He really isn't obstructive in that he himself is a Devil's Reincarnation (Hancock's, to be precise), and thus his aid as a combatant and his reasoning for not allowing the Fruit Brigade into Ponyville is actually sound. In fact, the only thing bureaucratic about his job is that he has to register all of the reincarnations.
Oh, Crap: Trixie when she learns Twilight is Celestia's student.
Noodle Incident: In their past life, Hancock and Alvida got into a battle over Luffy's heart that ended in a draw because he got bored. It resulted in Sanji crying for three whole days, and that was it.
There was an incident when Blueblood was a foal involving a pig and some crackers.
The last time Soarin' went without pie for a whole month.
Paper-Thin Disguise: Trixie's is simply removing her horn and renaming herself the Sly and Talented Mixie.
Parody Sue: Bluebell, Blueblood's sister: Popular, great singer, and Boa Hancock's reincarnation. In fact, she's really an illusion Blueblood created to impress Luffy's reincarnation, who he is in still in love with regardless of gender. Unfortunately for him, Luffy turned out to be reincarnated as Pinkie Pie, who is a mare.
Past Life Memories: For all Devil's Reincarnations, by dreams. As soon as the person starts developing their powers and accepting the fact that these are actual memories, the dreams become clearer, and they start taking on many of their past life's personality traits.
Poor Communication Kills: Glacier and Shining Armor don't like each other. Why? Glacier is really protective of Twilight due to the ties they had in their past life, and wanted to be able to protect her better now that the World Government is no longer standing in the way. Unfortunately, Shining thinks this is due to having romantic feelings for Twilight. Their dislike for each other culminated into a spar in chapter 20 after Glacier made a comment about Shining's fiancee impostor. Shining originally challenged him to a duel.
And now Spike, Rainbow Dash, Rarity, and Applejack are getting a level; Spike's learning sharpshooting, Rainbow Dash is learning Zoro's signature sword style, Rarity's learning how to use a staff, and Applejack's improving her kicking style.