Spoken Japanese has a number of dialects that vary regionally throughout the country. From my (moderately limited) Japanese language experience, most of what is spoken in anime is Tokyo-ben (aka Standard Japanese). I'm not great at telling the difference between dialects, however, so I was wondering, are non-Tokyo accents/dialects common in anime, or used at all? In shows like Yuri!!! on Ice, which is set in Kyushu, is a Kyushu accent being used or a Tokyo one? Do shows set in Kyoto use a Kyoto accent, or is everything standardized to a Tokyo-ben?
The answer depends on your definition of "common". Most anime don't include dialects or accents, so in that sense it's not "common" however it's not unusual for a show to do so. There are quite a number of shows that include characters with dialects, most often Kansai/Osaka-ben, but when they do it's almost always for a direct purpose.
- Igarashi Tora from Maid Sama! will occasionally speak in his native Kansai-ben (he's from Kyoto) when he's not acting like a perfect gentlemen as a sign that he's showing his true colors
- Ebina from Himouto Umaru-chan who, when nervous or flustered, occasionally slips into Akita-ben
- Mitsuha from Kimi no Na wa, who has a dialect to signify her status as a "country bumpkin" and it becomes relevant because she initially keeps her dialect when in Taki's body
Of course, it's not always that significant, as far as I can tell, the only reason Natsume from Inu x Boku SS speaks Kansai is to indicate his upbeat, outgoing nature. Perhaps for stereotype reasons?
That aside, it's rare for anime set entirely in another region to use said region's dialect. This is because all Japanese people can understand and speak Standard Japanese, aka Tokyo-ben, as that's what's taught in schools and show most on television. Therefore it's easiest to have Tokyo-ben speaking characters to ensure the whole audience can understand. The reason why Kansai-ben is the second most common is because a lot of comedians come from Osaka and so most Japanese people are quite used to hearing Kansai-ben and can understand it compared to others.
For reference, my mother's father's family lives in Aomori (most northern part of Honshu) and neither my mother (native speaker) or I can understand those relatives when they speak with the full dialect