Hmm...

basic: waterfox if it's like pokemon

technical: it all depends on the powers and attributes as well as strengths of each fox, If each fox is all the water in earth and all the fire in earth ever then if the fire fox was able to be close enough to the water fox to slowly evaporate the water then the fire fox would win but if it was slower than the waterfox then it would be extinguished by the waterfox with a large amount of the waterfox being evaporated but not completely destroying.

They're not pokemons they're browser y'know right? Also the winner can't be preticted, cuz they have the same powers, but they're like the opposite.

so if they have the same strengths and powers as well as skills and are complete opposites then there is no winner, because they would be in a constant stalemate with no one to intervene

Yes

well obviously water because water can extinguis fire easily

wasnt expecting that

waterfox because