The only advantage she has is sitting inside her pocket dimension or traveling to a distant galaxy, hoping for an eternal stalemate. And even pocket dimension may not work if you take what happened in Virtual On is taken as canon. Anything else is not going to work. Asteroid? The MF survived a continent crashing down. Teleportation? Ha ha, Index has it as common fodder play. Energy Stealing? Done that, didn't work.
To my knowledge, the only Isekai that has a chance against Accel is Rufas (this may be a stomp unless Virtual On is brought up, but even then if the last chapter bullshit is correct, then Rufas makes White Queen looks like a joke.), Rimuru (Time-Travel, if it still works on Accell due to angel business, otherwise he is also out.), annnd Mondaiji, (The series that has a magic god and probably unexplored class material as fodder and top player, respectively.) And some Isekai from Chinese and Murim novels.