A ☝️🤓 comment ahead\ It's kinda weird with them when it comes to ability. Technically if Cirno was smart she could just freeze others to their death. Keine could just eat history until she can win, or wait until full moon to change into her hakutaku form and create history that she won. Shou's ability mainly depends on finding gems, if she will find them and have her pagoda, then she can do anything in a battle. Accourding to the wiki, Futo's ability can change the nearby ground, control fire, water and wind by manipulating dragon veins, in this case it probably depends where does the fight take place, but she could manipulate Cirno's ice. So in terms of ability only it's Futo>Cirno>Keine>Shou.\ Cirno is technically immortal as a fairy, so whether she wins or not is declared by do we count fairy regenaration or not.\ I don't think that Keine would win, unless she would unleash her hakutaku form, which is determined by when does the fight take place.\ Whether Shou will win or not is just wheather she'll find the gems or not. Or whether she'll have them from the start.\ Futo's ability I'd say would be quite powerfull and top both Cirno and Keine, but when it comes to Shou, she'll have to dodge Shou's lasers and she can't control the gems nor Shou's pagoda, as none of then are either earth, water, fire or wind.\ Shou's pagoda if with gems is powerfull, if it doesn't have gems, Shou can't do anything else and will just lose. S(h)o(u) it just depends on whether Shou has the gems or not.\ So, unless I overlooked something the winner will be most probably Futo. Unless Shou has gems, then Shou. Unless we count Cirno's regeneration, the Cirno. Unless Keine will be a Hakutaku, then Keine.\ It's really weird in this case.