I'm learning Japanese, and I'm wondering if hiragana or kana is more common in Famicom and FDS games This is mostly a problem for saves in games like Kid Icarus. Thanks in advance!
Dialects are not very common, but the far most common is kansai-ben. Are you using the word dialect correctly? It has nothing to do with charset anyway.
I don't understand what you mean by charset either, all games have their own font and encoding. If you are talking about kana then katakana is the more common one in earlier games (Kid Icarus uses katakana only in text and the name entry screen), and hiragana is more common in later games. Games seldom use kanji other than on the title screen. Either way you need to memorize both hiragana and katakana properly and practice reading it. You can worry about kanji later.
This is the closest I've come across to dialect acknowledgment in FDS games : https://legendsoflocalization.com/the-legend-of-zelda/first-quest/
Yes Japanese western dialect is what's called kansai-ben as its the most famous dialect and has heavy associations to a funny or possibly less serious person in fiction. The wise-old-man-speech there is also very common although I don't know if it's a regional dialect or not. Most commonly you can spot it when they say "ja" instead of the standard "da" or the more formal "desu". I know some people that speaks like this, so this one isn't only used in fiction.