This is a tribute to Frozen II. Elsa looked really good in the sequel and now has true mastery over her abilities. Elsa may have had a bit of a difficult time with the water spirit but she would definitely be able to crush Nemo without much effort. Nemo isn’t fast enough to dodge the attacks nor is he durable enough to tank them. So in the end that puts him in a very dicey situation where there just isn’t a whole lot that he can do. Ultimately he will be facing complete defeat at every turn. Elsa wins.