I doubt he'd be fast enough unless you scale heavily from Ed's Cornello feat way back in the beginning of the manga.
or would Himiko Toga be good?
Remind me of what she can do please.
she should be Building level or higher via harming deku and her recent feats. she should be in the Supersonic- hypersonic range. her quirk is Shapeshifting, which allows her to change her appearance and can use the powers of those she shifts into. shes extremely skilled with knifes and needles and can take a rather large amount of damage.
idk much about medaka, besides all fiction, but rimuru has ability plus shared ones to deal with said all fiction.
with All of Creation, rimuru could understand the haxs presented(unless they have direct counters of being understood), and come up with a said plan for it. Infinite Prison would be a major act as it could seal the medaka(unless she has feats of resisting imaginary infinite space which not even multiversal levels of probability manipulation could take down).
void god could provide trouble as IS or Turn null could stall the box long enough to seal or use his Multi-Dimensional Barrier to block most of the attacks they have.
Harvest Lord Shub-Niggurath could provide assists to copy their abilities if its problemsome. heck, even with Avarice King Mammon: An ultimate skill that steal his opponents' souls, life, energy, abilities even their minds by re-writing the information in their soul can proberlly help unless they have resistance to it.
i believe with Information King-Akashic Records, which allows rimuru to use all abilities shown in the series would be too much for medaka.
there is FAR too many abilities to list but theses are only a tiny bit of what could help him win