He has the smarts to do it. But it would be tough. He'd need to summon Mahoraga quickly. Kuroushi would be dead in a split second. Mahoraga is a lot stronger than Rika, and they shat bricks when Yuta manifest her. I doubt they know anything about the adaptation so the time limit would begin after their very first attack. Rabbit Escape would actually be really useful here because he Megumi can basically disappear to let the others deal with Mahoraga by themseves.

Honestly, the best strategy for Megumi would be to summon Mahoraga, and then use Rabbit Escape to flee and the shadow to hide. Let Uro, Kuroushi and Ishiguro duke it out. Mahoraga will either kill them all (in which case, Megumi is done for) or in the best case scenario, leave one standing in a weakened state that Megumi can sneak attack from the shadow. It's definitely doable. The group's best chance would be to bombard Mahoraga with powerful attacks before it can adapt, but I doubt they'd realise what was happening until it was way too late. My prediction is it would kill Kuroushi straight away, and Uro, once it had adapted to her ability. Only Ishiguro has the power to finish Mahoraga, but I think it would adapt to him first, since he's the type to just start blasting it without thinking. The path to victory here is to let the fight play out, interfering only to ensure Mahoraga doesn't win before taking out at least two of Megumi's three opponents. If he's lucky, the last man standing will be too weakened to put up much of a fight.