Sonon Kusakabe is the guest party member in "Episode INTERmission" of Final Fantasy VII Remake Intergrade. Wielding a staff for a weapon, Sonon is not playable, but can be issued commands, and can be synergized with Yuffie Kisaragi to unleash devastating attacks on opponents (at the cost of a slower ATB buildup). Sonon's main role in combat, as well as to supplement Yuffie's damage, is to draw enemies away from her, as he is much more durable. His AI will also often match the player's actions, being more defensive or offensive.
Sonon is introduced partway through the first chapter of the episode, "Wutai's Finest". Thereafter, he accompanies Yuffie throughout the episode, and in the Shinra Combat Simulator, the two are treated as a single character when selecting the party.
Sonon's stats grant him higher HP and durability than Yuffie.
Sonon has three weapons: Marshalist's Staff, Indurate Staff, and Djinn Staff. Marshalist's Staff is his default weapon, has balanced attributes and teaches him the Swirling Storm ability. Indurate Staff teaches the Fighting Spirit ability, and gears its attributes more towards Attack Power. Djinn Staff is geared more towards Magic Attack.
Due to Sonon's lower MP and magic attributes in comparison to Yuffie, Sonon is more often than not better off with the Indurate Staff equipped. However, the Djinn Staff may be ideal for those using magic-based strategies.
He has various weapon abilities: "Twirling Lunge" is a spinning attack that increases an enemy's stagger; "Swirling Storm" continues targeting an enemy while dealing increased damage; "Fighting Spirit" strikes an enemy multiple times dealing high damage; and "Incite" draws the attention of a weakened enemy until Yuffie deals a certain amount of damage. Sonon's limit break, "Dance of the Dragon", delivers myriad blows and deals high damage.
In terms of armors and accessories, Sonon greatly benefits from the Firebird Armlet, since non of his weapons have the Reprieve passive ability. In terms of accessories, the Kindred Cord helps to remedy some of his ATB problems, since it reduces the cost for synergized abilities.
Sonon cannot be controlled, but can be issued a few commands of his own. His default command ability is Twirling Lunge, a spinning attack that increases an enemy's stagger gauge, and can be effective at bursting down a boss more quickly. Swirling Storm, learned from using it while equipping his Marshalist's Staff, is a simple physical attack that can deal high physical damage to a target. Fighting Spirit, learned from using it with his Indurate Staff equipped, causes Sonon to focus down a target and deal high physical damage with multiple blows; this ability is imperative to make him generate ATB faster on his own. Incite, his ability from the Djinn Staff, draws a weakened enemy to Sonon until Yuffie deals enough damage.
Though Sonon's command abilities have their use in battle when he is not synergized, most of his ATB charges will be spent on using synchronized abilities. Using Synergized Art of War for physical damage and Synergized Windstorm for magic damage can devastate enemies, but expends a charge of ATB from both Yuffie and Sonon.
Sonon has a passive ability Final Sacrifice: when Yuffie is KO'd, Sonon will revive her at the cost of being KO'd himself. There is no limit to this ability; he'll use it indefinitely whenever Yuffie is KO'd. However, Yuffie needs to synergize with Sonon to be revived after Nero's instant death attacks.
Because Sonon cannot be directly controlled, materia that require specific player input will not function, with the exception of Ninja Cannonball Materia, which will function regardless of who equips it. As one of Sonon's main roles regardless of how the player builds him is to be the party tank, he can always benefit from HP Up Materia, and will want Provoke Materia, at least until he learns Incite.
Though most of Sonon's damage will be physical, he can make use of Magic Materia effectively when he uses the Synergy Materia. This is because synergy materia allows spells to be cast without expending any ATB or MP, alleviating Sonon's deficiencies in both areas. With Djinn Staff equipped and synergy used, Sonon can be viable in a magic damage role. Aside from dealing damage, Sonon can benefit from the second Magnify Materia available in "Episode INTERmission"; paired with Time Materia or Barrier Materia, it can benefit both party members. Buffing spells are equally effective even when cast with lower Magic attribute.
ATB Stagger Materia is more useful on Sonon than most, because he cannot be controlled. This allows him to build his ATB without needing to get in his own attacks. Skill Master Materia can also help alleviate Sonon's problems in building ATB himself.
Synergized has Yuffie and Sonon combine their strengths at the cost of ATB filling slower. To synergize, both Yuffie and Sonon need to be in the party and both party members must be alive. When synergized, Yuffie and Sonon focus on the same opponent and Sonon will match Yuffie's damage type (physical weapon strikes or magical ninjutsu). The pair can use Synergized Art of War, Synergized Windstorm, Ninja Cannonball, and (with Sonon's Marshalist's Staff sufficiently upgraded), synergized limit break. Being synergized has many benefits outside of the specific compatible abilities. The pair is not as easily interrupted and recover from being knocked down faster. The pair can double up their magical ninjutsu skills, which is especially good for staggering some enemies with an elemental weakness. Simply attacking a Pressured enemy when synergized can stagger them fast. Precision-guarding while synergized causes Sonon to counterattack Twirling Lunge with no ATB cost.
Sonon's limit break is Dance with the Dragon, an attack that deals myriad blows aimed at one target and can deal high physical damage. When synchronized, Sonon can join this limit break with Yuffie's Bloodbath in Synergized Limit Breaks to deal enormous damage to one foe; doing this can be difficult to achieve without the Götterdämmerung, however.
His victory pose in the Combat Simulator is to twirl his staff above his head, briefly plant it in the ground, and then place it on his back.