Nintendo will be releasing Pokemon Sun and Pokemon Moon in nine languages later this year, two of those languages are Simplified and Traditional Chinese. A result of language barriers being torn down for Chinese gamers was a name change for a series icon: Pikachu.
Pikachu's name was being changed from the longstanding Cantonese pronciation to the Mandarin pornunciation, something that changed the sound Pikachu's name quite a bit. Well, at least enough for fans to protest over the issue.
However, it should be noted that the protests were linked to another movement in China that looked to protect the Cantonese language from being erased, as some citizens believe is happening. Essentially, the Pikachu protests were fueled by some other political movement.
A statement from Nintendo's Hong Kong division has released a statement on the matter, saying that no matter how the word looks, Pikachu's name should be pronounced with the global pronunciation:
Following the announcement of Pokémon Sun/Moon info in May 10th, the new names of the 151 Pokémon appeared in Pokémon Red/Green was also announced. However, the suggestions in the petition was not reflected in the info announcement. At the same time, we did not give detailed explanations, causing severe negative reactions. We sincerely apologize for causing this inconvenience.
The decision of the inclusion of additional language in Pokémon Sun/Moon was reached after discussion between Nintendo and The Pokémon Company. To help everyone understand the development concept of Pokémon Sun/Moon…
As for the Chinese name of Pikachu – it will be displayed as「皮卡丘**」in game. However, we never intended to restrict the pronunciation as「皮卡丘 (PeiKaaJau)」, instead we wish that the global pronunciation “Pikachu” will be used. Because of that, whenever the name「皮卡丘」appears in marketing and promotional materials, the pronunciation “Pikachu” will be used.
We understand the unfamiliarity caused by changes in the pronunciation of some Pokémon
Basically, Nintendo said "Yeah, we saw your protests. Sorry you're upset, but wer aren't changing anything. Oh, and it's Pee-ka-choo."
[Nintendo Everything has the full translated statement from Nintendo]