We talking about the same Mereoleona who burned through one of Yami’s signature attacks with a casual punch right? You’re saying this Mereoleona wouldn’t be able to counter Yami?
Rhya had to heal himself after every single attack from Mereo. Really there is no evidence that Mereo wouldn’t just one shot Yami or otherwise severely wound him with each attack she lands on him while easily burning every one of Yami’s spells to ash.
Yami is the one who needs to prove he can counter Mereoleona, she has already proven that she can easily counter Yami because she is at least a tier above him in strength.
Rhya had to heal himself after every single attack from Mereo. Really there is no evidence that Mereo wouldn’t just one shot Yami or otherwise severely wound him with each attack she lands on him while easily burning every one of Yami’s spells to ash.
Yami is the one who needs to prove he can counter Mereoleona, she has already proven that she can easily counter Yami because she is at least a tier above him in strength.
Speed isn't the only area where he has her beat. She has no answer to Black Moon which can erase spells or Black Hole that can suck in even light and momentarily immobilize the attacker?(skimmed through these chapters only once so I can't recall exact details). You're not going to tell me she can just burn em all because she burned a lightless slash which wasn't even from Yami, are you? Even if she can burn through all of Yami's spells which doesn't even make any sense in the first place; Yami can still one shot her via dimension slash or death thrust both of which can't be countered with fire.
Yami's arsenal is filled with abilities way too broken and he's too skilled to not to be able to make use of them even against Mereoleona. Even when you look at the opponents they fought, Yami has the clear edge over her because he fought and basically won against someone far stronger than anyone Mereoleona has ever fought. Even now, her best feats are against one of many minions of Dante while Yami defeated the main-boss himself so we have no reason to place her above current Yami.