>Hoenn
Gen 1 is Over represented by 10%
Gen 2 is Under represented by 10%
Using this as an example, Gen 1 made up 60% of the old Pokemon at the time and 70% of the ones in the Hoenn Pokedex.

>Sinnoh DP
Gen 1 is Over represented by 7%
Gen 2 is Over represented by 6%
Gen 3 is Under represented by 12% (the most under represented in the series)

>Sinnoh Platinum
Gen 1 is Over represented by 3%
Gen 2 is Over represented by 7%
Gen 3 is Under represented by 10%

>Unova B2W2
Gen 1 is Under represented by 4%
Gen 2 is Over represented by 2%
Gen 3 is Over represented by 2%
Gen 4 is Over represented by 0% (reminder that all these numbers are rounded to the nearest whole number)

>Kalos
Gen 1 is Over represented by 6%
Gen 2 is Over represented by 1%
Gen 3 is Under represented by 0% (the most balanced in the series)
Gen 4 is Under represented by 3%
Gen 5 is Under represented by 3%

>Alola SM
Gen 1 is Over represented by 18% (the most over represented in the series)
Gen 2 is Under represented by 0%
Gen 3 is Under represented by 4%
Gen 4 is Under represented by 2%
Gen 5 is Under represented by 9%
Gen 6 is Under represented by 4%

>Alola USUM
Gen 1 is Over represented by 10%
Gen 2 is Over represented by 2%
Gen 3 is Under represented by 3%
Gen 4 is Under represented by 4%
Gen 5 is Under represented by 7%
Gen 6 is Over represented by 1%

>Galar
Gen 1 is Under represented by 2%
Gen 2 is Under represented by 2%
Gen 3 is Under represented by 4%
Gen 4 is Under represented by 1%
Gen 5 is Over represented by 7%
Gen 6 is Over represented by 1%
Gen 7 is Over represented by 0%

>Paldea
Gen 1 is Under represented by 2%
Gen 2 is Over represented by 2%
Gen 3 is Under represented by 1%
Gen 4 is Over represented by 4%
Gen 5 is Under represented by 6%
Gen 6 is Over represented by 1%
Gen 7 is Under represented by 1%
Gen 8 is Over represented by 3%