Poroshenko is working hard supporting the war effort. He has never been overjoyed about Zelensky (who beat him in the last election, and there was a peaceful transition, but later treason charges were brought against him). He has done a lot to supply armaments.
Tymoshenko is a former PM and of course met Putin when she was able to out-Slav him post-Orange revolution. Half my older relatives loved her when she was at her peak.
Both are figures from the Maydan Revolution, but neither were really there (see Spiegel image). Neither was Zelinsky but that is an opaque use of Russian language arguments rabbit hole. Klitschko was, and has a niche position as Kyiv Mayor. Zelinsky somehow hasn't managed to sack him. Yulia was of course imprisoned during the Revolution of Dignity protests, until right at the end when there was the Yanukovych collapse and flight. Poroshenko defeated her in the post-Maydan Presidential election.
Images: Yalta agreement signing in 2009. Putin was Russian PM at the time, observing a constitutional nicety and letting Medvedev be President (Yushchenko key figurehead of the Orange Revolution was Ua President then).
Yulia Tymoshenko in a wheelchair, freed from prison and with enough time to fix the braids, addressing the revolutionary crowd.
Poroshenko the mediator being told 'Piss of you Jewish Garbage'.
Klitschko sprayed by a fire extinguisher during Euromaydan.