The 5th generation of portable game consoles, which can more accurately be described as the “Game Boy Color + failures” generation (although, to be fair to the WonderSwan, it did alright). With this sort of name, it's no surprise to hear that this is commonly considered as having began in 1998 with the release of the Game Boy Color, although some may claim 1997 with the release of the Game.com. In contrast, the period which it ended is easily determined, as most would consider that year to be 2001, when the Game Boy Advance released. In a way, this generation was a sort of “stopgap” between 4th and 6th, as it never really possessed it's own distinct identity outside of “Game Boy Color”. Despite this, the 5th generation is the 1st generation to have a powerful array of EOPs, although this is again, almost entirely thanks to the Game Boy Color.

See Bandai Wonderswan (+Color).

Has a calendar, a world clock, a horoscope(??), and an alarm. Better than nothing. Unknown if this is on the non-color NGP.

https://www.youtube.com/watch?v=TA9NHlbgA6I

See Nintendo Game Boy Color.

See Tiger Game.com.