Sorry for such a late answer, I’ve been busy these past days. Alright, let’s start with Q. By the way, I dunno what is Q’s gender? So I will just use ‘they’. This one is kind of short since while Q has done so much chaos in the story, Q has never appeared again in canon so it’s hard to really see more of their Ability.

All images are from easygoingscans

Yumeno Kyusaku aka Q, Port Mafia’s most fearsome member and actually sealed because of it. Their Ability, Dogra Magra, is a mind control ability that pushes their target to become berserk and attack everyone.

Q’s Ability only works against people that had hurt them, so their Ability is supposed to be a counter-type thing. However, Q intentionally hurt themselves (by wrapping their arm with razor blade attached to a wire, making that the slightest touch anyone accidentally (or Q touches their arm to them) can be included in ‘hurting’ them and their Ability can almost activate at will now. I said almost because Q still can’t do anything if their target avoids them or is too far for them to touch.

(Q’s arm wrapped in wires with blades)

Q’s Ability or it can be said, ‘curse’, leave behind a mark (like curses from ghost stories) which can appear in any part of the victim’s body and shaped like a palm of a young child. The media for said curse is Q’s doll, which was created from Q’s Ability. If Q breaks apart the doll (it doesn’t have to be Q, anyone can activate the curse by breaking the doll if Q can’t do it for some reason. However, Q first has to ‘mark’ their victims or the curse will probably activate without any target. One doll can be used for more than one person, as seen by when almost the whole Yokohama fell into Q’s Ability when one doll was torn apart. The doll can laugh and speak, mostly taunting other people. It can even destroy itself).

When Q breaks the doll, the target will experience hallucinations in which everyone else are mind controlled and attacking the target, which will leave the target no choice but to protect themselves (it’s unclear if this is the only hallucination someone can experience while under Q’s mind control, since it’s the only time we can see into the mind of the victims. The victim may feel that they are only protecting themselves, but maybe Q also boost their own preservation instinct/arrogance/their desire to help others that made them fight back if the target usually won’t attack innocent people like Kunikida and Atsushi).

Usually, Q’s Ability is limited to only people that they can have direct contact with (since Q needs to bump or touch them to make their target hurt them), but for once in BSD we actually see if Abilities interact together and joined forces. John’s Ability to connect himself to the plants are now used on Q. With their senses joined with the plants, Q was hurt again and again by civilians who ignorantly went around with their daily activities (stomping on roots, picking a flower, trimming branches, etc), all of this pain went into Q and so, Q can use their Ability to almost everyone in Yokohama at once.

(Now I want to see other Abilities working together. Hmm... wonder what Abilities can join together so well like John and Q? Is this considered a Singularity?)

In combat, while Q doesn’t directly fight in combat, they can be a deterrent that hold the enemy attack. If they don’t know about Q’s Ability, Q can be a pretty devastating trap. While all the enemy attack them at once, Q then can activate their Ability and make the enemy’s side break apart because they start to attack each other in mad frenzy. If the enemy know about Q’s Ability, they will be unable to attack in fear of accidentally activating Q’s Ability.

However, Q’s Ability doesn’t differ between friend and foe. If there is any friendly-fire between Q’s comrades, then they will also fall into Q’s mind control. It’s unknown whether Q can select the people that their Ability affect or it just affect everyone that hurt him.

So, against people with Abilities or not, Q can be a very troublesome opponent. It’s also unclear to what extent their Ability can ‘blame’ someone for any pain Q get. For example, let’s say... what if Chuuya chuck a boulder at the enemy and then a piece of it bounced and accidentally landed on Q’s head. Will it still be counted as Chuuya’s attack against Q? Chuuya may fling the boulder, but a piece of it wasn’t counted as the attack. The boulder is an inanimate object that bounced because of gravity (not Chuuya’s gravity) or wind and landed on Q. Can Q still blame Chuuya for that stone when it’s not Chuuya’s fault but the nature? Or if Dazai left behind Mori’s scalpel as a trap against Q, will Q’s curse target be Dazai (let’s just ignore the fact that Dazai won’t be affected by the curse for the sake of this example) or Mori if Q doesn’t know that it’s Dazai’s fault and instead blame Mori? Will Mori be the one to receive the curse instead of Dazai, who is the true culprit?

(When Q is connected to the plants and his curses landed on everyone without fail, it can be argued that since their senses are connected to the plants they can ‘sensed’ people who have hurt them. But if it wasn’t because of that, then Q’s curse will only mark people that have hurt them. If even the most accident of accident can still invoke Q’s curse, then their comrades really have to tip toe around Q. It’s also unclear why Q didn’t immediately activate their curse by having the doll rip itself apart the moment they had marked the people of Yokohama. It can be that Fitzgerald and the others stopped the doll from tearing itself down, but it can also because there is a limit in distance of how much Q can move the doll)

Q doesn’t seem to have any combat capability, although at that time Q’s opponent is Lovecraft which... well... but their aversion to direct combat can be a proof that they aren’t really good at it, despite the fact that just like Chuuya, direct combat is when their Ability can be used in full. Just imagine if Q can fight almost as good as Chuuya. They can go around to the battlefield, letting the enemies get a few good punches and then faking retreat. When the enemies that had hurt them went back to their base, Q can activate their curse and then the mind controlled victims will then rip apart their own organization.

Q’s biggest enemy is probably Dazai, since Dazai can purify (heh) the curse when he got the doll. Q can probably hide the doll somewhere safe (what if someone destroys Q’s doll? Will the mind control go on forever or will it disappear?) to keep Dazai from nullifying his Ability, although Dazai is also a really clever person and with Ranpo’s help he can find Q’s doll quickly.

If Q’s attacker can snatch away the doll from Q’s hand or limiting his movement (Akutagawa’s Rashoumon to steal the doll and bind him, Demon Snow, etc), they can prevent Q from activating their curse. If they also can kill Q in one hit without giving them a chance to activate it is also preferable. The fact that Q or someone else has to tear down the doll is probably Q’s biggest weakness, because their curse can’t activate immediately. This give some leeway for their enemy to attack him, keeping in mind of Q’s doll. But this also means Q’s comrade can sacrifice them. Let Q absorb all the attack and even if Q is unable to activate their Ability on his own, their comrade can just tear down the doll in their place. It is unclear whether his curse will still stay if Q dies, but if it does, then Q only became even more dangerous.

Also, while Q’s Ability is said to be mind control, it’s unknown to what extent Q can control their targets. Is Dogra Magra can only make their target insane and attack everything in sight? Or can it be used for a more ‘classic’ mind control like controlling them to be loyal to Q and do everything for them? Unfortunately it’s easy to see whether someone has been controlled by Q or not by looking at their face. Q’s victims usually has blood streaking down from their eyes. Can Q look at their mind and control what hallucinations they see? If so, Q can know what it is their biggest fear or worry, and compiled for later blackmail if needed. Does it leave a scar in their mind?

Fighting Q is unlike fighting other Ability user. The problem is not done just by defeating Q, but is also to make sure their Ability won’t activate. Q’s Ability is the second in rank of the sheer destruction it can bring. The moment Q is in the board, people will have to actively trying to seal them again just because of the high risk they can bring. Because Q and their Ability is uncontrollable, really like a zombie virus that keep on spreading and wreaking havoc in it’s wake. In fact, I wonder why Mori even let out Q in the first place. It’s just too risky of a move in my opinion. Q is more likely to bring chaos to the town that Mori is supposed to love rather than helping his plan at all. Without Dazai at the mafia side, Mori literally has nothing to keep Q in check. Then again, no one knew what was in Mori’s mind when he thought of that. Maybe he has a plan? That is for Q, I think.