Fukasaku holds the elemental advantage here with having wind and water where as Shima has fire and water. Now of course wind+fire is deadly, but that requires Shima creating enough time to fire one after the other without retaliation.
Zessenbaku and Zessenzan are both extremely fast, but the size here works in Shima's advantage as Fukasaku actually has to hit her with it, where as she can use her acid and just get close to Fukasaku and end him.
It'd be pretty interesting, but I'd give 'Baku the edge over 'Zan and thus the edge to Shima overall.