Yusaku is definitely Mycroft, as Both Yusaku and Mycroft are better than Shinichi and Sherlock respectively at deductions but in Mycroft's case he is lazy and prefers to be alone with his brain most of the time: he is in the Diogenes club after all. In Yusaku's case, he is better at deductions but he is a writer and thus doesn't spend much time solving practical mysteries. The effect is the same, neither are out on the ground working most of the time.
As for Irene Adler, she only showed up once in Sherlock Canon - "
A scandal in Bohemia". The rest is expanded on by people who are not sir Arthur Conan Doyle. (fanfictions if you will...) In "A Scandal in Bohemia", Irene Adler, who was an excellent concert singer and actor, had with her a compromising photo of her and the hereditary king of Bohemia in a romantic affair which would be bad if it got out. Irene has been threatening to send it to him and ruin his upcoming marriage. She would not give in for money, nor could the picture be found when the king's men ransacked her house. Sherlock was tasked to retrieve it. Sherlock went out in disguise to stake the house out and then wound up in a ridiculous situation helping Irene and a lawyer get married. Sherlock still doesn't have the picture yet, so he calls upon Watson and forms a plan. Sherlock enters the apartment by getting into a brawl and becoming injured. Next Watson takes a smoke bomb and toss it through the window when Sherlock signals. He and several other paid off people shout "fire!" After doing all that and rendezvousing, Sherlock explained how the plan went to Watson. Irene rushed at once to the hiding place of the picture in fear so now Sherlock knows where it is. As they were leaving someone in a familiar voice says "good night" to Sherlock. I'm too lazy to type out the rest so read it to yourself by clicking on the link I gave above. It's a short read.
Haibara is... a little different from Irene. In some ways she is similar, in others not. Irene never loved Sherlock. Sherlock admired Irene, but if Watson is to be believed Sherlock is not capable of love. In several ways, Irene reminds me more of Vermouth than Haibara. Both are actresses and are good with disguises. Both were tricked by the detective into revealing an important secret, and then despite retaining incriminating knowledge in the end, safeguards it instead. Both give her word that she won't use it against the protagonist or his client in the case of Irene, and Conan and Haibara in the case of Vermouth.
Holmes - Shinichi
Watson - There isn't really one person who fills this roll as Shinichi doesn't pick up a helper. Sometimes Ai fills this roll, other times Agasa.
Irene Adler - Vermouth
Lestrade - Mouri Kogoro or the police force in general.
Mycroft - Kudo Yuusaku
Moriarty - the boss
Moran - Gin especially but also Chianti, Korn, or Vodka...
Baker Street Irregulars - The detective boys.
HayleyStark wrote:
Gin is quiet smart but he's not the one who moves everybody around in the Black Org. Apparently Vermouth is his superior.
According to the Official DC stuff Vermouth and Gin are of equal rank. Pisco was on a rank equal with Gin and Vermouth as well but because he made a mistake...