Like say I send my nidoking out on a male machamp. Nidoking gets the 25% boost and kills machamp. Next a blissey comes in. Will his attack drop because now a female has came in? or would it stay on the boost that he gained from male machamp
His attack would drop when Blissey switched-in.
Rivalry's damage boost only stays if your current opponent is of the same gender,so when Blissey switches in Nidoking's power should drop.
