>Gen 1
technically Rhydon(1990, six years before Red/Green were released)

>Gen 2
Ho-oh(August 1996, three years before Gold/Silver were released)

>Gen 3
Keckhon, Azurill and Wailmer(March 2001, 1 year and 8 months before Ruby/Sapphire were released)

>Gen 4
Munchlax(May 2004, 2 years and 4 months before Diamond/Pearl were released)

>Gen 5
Zorua and Zoroark(February 2010, 7 months before Black/White were released)

>Gen 6
Chespin, Fennekin, Froakie, Xerneas and Yveltal(January 2013, 9 months before X/Y were released)

>Gen 7
Magearna(February 2016, 9 months before Sun/Moon were released)

>Gen 8
Grookey, Scorbunny and Sobble(February 2019, 9 months before Sword/Shield were released)

>Gen 9
Sprigatito, Fuecoco and Quaxly(February 2022, Scarlet and Violet are coming out later this year)

Why'd they stop revealing next-gen Pokémon super early after Gen 4?