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spelling/grammar standards: You may use the pronoun "who" instead of "which" or "that" and use "he" or "she" to refer to Pokemon as people if you so desire. It must be consistent for the entire article or analysis if this is done, however.
Analyses are a bit different. I've only seen gender-neutral pronouns as acceptable in C&C unless the Pokemon being talked about is limited to one gender, such as Blissey. I don't agree with the arbitrary assignment of male to Aegislash or female to Venusaur, etc.
It's just generally a lot cleaner and more straightforward to address most Pokemon as "it". "Whose" is acceptable in some contexts, but in the case where that would be used, I would usually find an alternative way to write the sentence.