Shiro
Parent Ryoma
Default Class: Spear Fighter
Recruited on: Paralogue 7: Father & Liege
Possible Mothers/Fathers: Azura, Camilla, Elise, Felicia, Hana, Kagero, Mozu, Oboro, Orochi, Rinkah, Setsuna
Shiro is one of the potential powerhouse melee damagers, considering the Swordmaster skills his father can pass down to him. His unique skill is Noble Cause which gives him +3 damage when paired with a damaged unit but suffers +1 damage as a compensation. If Rinkah is her mother, he gains access to deadly Oni Chieftain skills like Counter and Death Blow. Here's a sample rundown of his potentially devastating skills:
Astra (Swordmaster) : Deals five consecutive hits with half of the projected damage
Death Blow (Oni Chieftain) : When Shiro initiates the battle, he gains +20 Crit
Vantage (Samurai) : Unit attacks first when HP is below 50%
Counter (Oni Chieftain) : When an adjacent enemy attacks Shiro, he deals 100% damage back to the attacker
Life or Death (Master at Arms): Deal +10 damage dealt and +10 damage received.
Kiragi
Parent Takumi
Default Class: Archer
Recruited on: Paralogue 8: A Great Hunt
Possible Mothers/Fathers: Azura, Camilla, Elise, Felicia, Hana, Kagero, Mozu, Oboro, Orochi, Rinkah, Setsuna
His unique skill, Optimist will give him +4 SPD and +8 LCK when you use the "Wait" command. This is much more of a defensive ability. With Hana as her mother, Kiragi can take advantage of his unique skill by learning Vantage (Unit attacks first when HP is below 50%) as long as he's not attacked from an adjacent space. Similar to Shiro, if Kiragi's mother is Rinkah, he gains access to the deadly Counter skill which also complements his unique skill. (It's better to have Rinkah learn the skill first then just pass it down to Kiragi instead) That said, place him always on the second space behind a wall or tank so he can counterattack as necessary. In the other hand, with Azura as her mother, he gains access to the Kinshi Knight class while retaining his bow proficiency.
Asugi
Parent Saizo
Default Class: Ninja
Recruited on: Paralogue 9: Saizo vs Saizo
Possible Mothers/Fathers: Azura, Beruka, Charlotte, Felicia, Hana, Hinoka, Kagero, Mozu, Oboro, Orochi, Rinkah, Sakura, Setsuna
Sweet Tooth is Asugi's unique skill which recovers his HP by 4 when he ends his turn with "Wait". Asugi starts with most of his father's skills handed down to him. With Kagero as the mother, his class-related stats are improved but makes his skills redundant and limits his re-class options. You can consider other potential mothers with skills that will complement his skills, if you want him to maintain the ninja class set.
Selkie
Parent Kaden
Default Class: Fox Spirit
Recruited on: Paralogue 10: Hunter & Prey
Possible Mothers/Fathers: Azura, Charlotte, Felicia, Hana, Hinoka, Kagero, Mozu, Oboro, Orochi, Peri, Rinkah, Sakura, Setsuna
Selkie's unique skill is Playthings which makes enemies around her lose 5 HP at the start of her turn. This could've perfectly gone well with the Malig Knight's Savage Blow (when the unit initiates Combat, all enemies within two spaces will lose 20% HP at the end of battle) but unfortunately, Kaden can't pair with Camilla or Beruka. If Rinkah is her mother, she gains access to deadly Oni Chieftain skills like Counter and Death Blow. LV15 Nintetails class also gives Selkie access to the Grisly Wound skill, another HP lowering skill. With those skills under her belt, she can be a good vanguard unit as long as she has good healers behind her.
Hisame
Parent Hinata
Default Class: Samurai
Recruited on: Paralogue 11: A Long Grudge
Possible Mothers/Fathers: Azura, Felicia, Hana, Hinoka, Kagero, Mozu, Oboro, Orochi, Peri, Rinkah, Sakura, Selena, Setsuna
Hisame's unique skill is Calm which gives him +4 Res/Skill when ending his turn with the "Wait" command. Swordmaster skills like Vantage will allow to him to take advantage of his wait-triggered skill. Rinkah will give him access to even more powerful skills like Counter and Deathblow.
Mitama
Parent Azama
Default Class: Shrine Maiden
Recruited on: Paralogue 12: Sweet Dreams
Possible Mothers/Fathers: Azura, Beruka, Effie, Felicia, Hana, Hinoka, Kagero, Mozu, Oboro, Orochi, Rinkah, Sakura, Setsuna
Mitama's unique skill is Haiku, which triggers if there are two allies in a vertical line and they each rcover 5, 7, and 5 HP. Fixed HP recovery doesn't help that much especially in later chapters so having access to better healing options like Renewal is essential to be able to use her properly. Hinoka gives her access to the Falcon Knight class which is basically a flying naginata/spear wielder / healer. Other melee-type fighters who will become her mother will just make give her offset adjustments to her otherwise low STR rating. Sadly, due to her father's unappealing personality, most players may not always carefully consider her skill inheritance.
Caeldori
Parent Subaki
Default Class: Sky Knight
Recruited on: Paralogue 13: Truly Talented
Possible Mothers/Fathers: Azura, Felicia, Hana, Hinoka, Kagero, Mozu, Nyx, Oboro, Orochi, Rinkah, Sakura, Selena, Setsuna
Caeldori strongly resembles the reknown Pegasus Knight in FE: Awakening (Cordelia), down to the personality. Even her JP name is a re-arranged version of her original name (Tiamo - Matoi). If you want a red-head Caeldori (vanilla), the best mothers for her will either be Hinoka or Selena. Hinoka will be able to pass her skills through the class options will be limited since her father has the same class. Selena in the other hand offers additional class options and gives Caeldori access to good self-sustaining skills like Good Fortune (Recovers 20% HP of the user, trigger LCK%) and Sol (Half of damage dealt is restored to HP).
Rhajat
Parent Hayato
Default Class: Diviner
Recruited on: Paralogue 14: After the End
Possible Mothers/Fathers: Azura, Effie, Felicia, Hana, Hinoka, Kagero, Mozu, Nyx, Oboro, Orochi, Rinkah, Sakura, Setsuna
Like Caeldori, Rhajat's name and appearance is tribute to another popular mage in FE: Awakening. Nyx offers additional magic-based class while also maintaining high magic stats for Rhajat compared to Orochi who is from the same class-set.