Every game except PLA and SV work off of real-time, (though Ultra Moon is inverted.) This means that whatever the time is set to on the analog clock in-game or the clock in your system settings will be the time in-game. Remember that in Generation VI and Generation VII, time based events are stopped for 24 hours after changing the clock.
In GSC, Morning is from 4:00 AM to 9:59 AM, Day is from 10:00 AM to 5:59 PM, and Night is from 6:00 PM to 3:59 AM.
In Generation III, there is no proper "day-night cycle," as the tint of the game never differs between day and night. However day-based evolutions occur between 12:00 PM and 11:59 PM, while night-based evolutions occur between 12:00 AM and 11:59 AM.
In Generation IV, the three time periods from GSC return. Morning lasts from 4:00 AM to 9:59 AM, Day lasts from 10:00 AM to 7:59 PM, and Night lasts from 8:00 PM till 3:59 AM. From 5:00 PM till 7:59 PM it is considered twilight, but this is purely visual.
In Generation V, the day-night cycle changes by the season, akin to how it does in real life. In the Spring, Morning lasts from 5:00 AM - 9:59 AM, Day lasts from 10:00 AM - 4:59 PM, Evening lasts from 5:00 PM - 7:59 PM, and Night lasts from 8:00 PM - 4:59 AM. In Summer, Morning lasts from 4:00 a.m. - 8:59 a.m, Day lasts from 9:00 a.m. - 6:59 p.m, Evening lasts from 7:00 p.m. - 8:59 p.m, and Night lasts from 9:00 p.m. - 3:59 a.m.
In Autumn, Morning lasts from 6:00 a.m. - 9:59 a.m, Day lasts from 10:00 a.m. - 5:59 p.m, Evening lasts from 6:00 p.m. - 7:59 p.m, and Night lasts from 8:00 p.m. - 5:59 a.m. In Winter, Morning lasts from 7:00 a.m. - 10:59 a.m, Day lasts from 11:00 a.m. - 4:59 p.m, Evening lasts from 5:00 p.m. - 6:59 p.m, and Night lasts from 7:00 p.m. - 6:59 a.m
In Generation VI, Morning lasts from 4:00 AM till 10:59 AM, Day lasts from 11:00 AM till 5:59 PM, Evening lasts from 6:00 PM till 8:59 PM, and Night lasts from 9:00 PM till 3:59 AM. In ORAS, the game will always start at daytime and will only align with the 3DS clock when the analog clock is interacted with.
In the Sun and Ultra Sun games of Generation VII, Morning lasts from 6:00 AM till 9:59 AM, Day lasts from 10:00 AM till 4:59 PM, Evening lasts from 5:00 PM till 5:59 PM, and Night lasts from 6:00 PM till 5:59 AM. In Moon and Ultra Moon, these times are all the opposite, (e.g, Morning starts at 6:00 PM.) LGPE is set in perpetual daytime.
In Sword and Shield, Morning lasts from 6:00 a.m. - 9:59 a.m, Day lasts from 10:00 a.m. - 6:59 p.m, Evening lasts from 7:00 p.m. - 7:59 p.m, and Night lasts from 8:00 p.m. - 5:59 a.m.
The cycle of BDSP is believed to be the same as Gen IV.
In PLA, every real minute is an hour in-game. Morning lasts for 7 minutes, midday lasts for six minutes, evening lasts for 3 minutes, and night lasts for 8 minutes. You can change the time by resting at your quarters or base camp.
SV uses it's 72 minute cycle, where the first 18 minutes are morning, next 18 are midday, next 3 are evening, and last 33 are night. This repeats 20 times every 24 hours. When playing in co-op, all players are subject to the same time as the host's game.
Source
That should cover it! My thumbs hurt. Hope this helps.
