Sorry, but "who can beat xxxx" type matches are not allowed to be voted on for Over the Limit threads.
And isn't Mxyzptlk a Nigh-Omni? Same for Bat-mite and the Demon lords?
Mr. Mxy and Bat-Mite are only notable for their high-level of reality, spatial and time manipulation. They aren't omnipresent nor omnipotent. Same deal with the Demon Lords.
But isn't Haruka too inexperienced to use the full extent of her powers?
While Haruka indeed has inexperience with his powers, the abilities you highlighted with this version of Kars don't seem to involve reality manipulation as they involve variants of time, spatial and causality manipulation. Haruka could exploit this with her power.
Also why Mephisto? He's not even on Galan's level.
Mephisto's highly implied to be multiversal-level since he has created several parallel universes through his interactions with Peter Parker. And unless he has the Ultimate Nullifier on him, Galactus and the cosmic entities of Earth-616 he is associated with are only universal-level.
(Not sure about Jim)
Jim's multiversal level with his reality warping and considered a megaversal-level threat as one of his parallel counterparts was successful in taking over an entire megaverse since his power couldn't be stopped and the Earth-238 universe had to be completely destroyed to halt the power coming from that version of Jaspers. He's easily among the strongest non-godlike reality warpers within Marvel Comics.