Suggested by iKnowledge All right so if power wasn’t enough to stop Isshiki Ōtsutsuki then how about speed? Reverse Flash has certainly got a whole lot of that after all. Well, he may be able to dodge some attacks but when it comes to combat speed I would say Isshiki has the edge here. His abilities also have a very wide range of attack so that will make dodging them even tougher for the Reverse Flash. Ultimately I’m not convinced that he would be able to do more than briefly put up a fight. Isshiki Ōtsutsuki wins.
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Given how Thawne is fighting people who are close to him in power and given the Speed Force’s range compared to what existing speeds we know about, I wouldn’t count out Reverse-Flash. My defense will rest after this: https://vsbattles.fandom.com/wiki/Professor_Zoom_(Post-Crisis).
For sure he’s a very fast fighter but I don’t see him being able to do a whole lot against someone like Isshiki. Isshiki’s power is just absolutely nuts, even Naruto was unable to outspeed him in his chakra cloak mode