Why do people complain about the lack of new Pokemon in gen 6 and 7? It's not that different from some of the other generations.
Gen 1 = 151
Gen 2 = 100
Gen 3 = 135
Gen 4 = 107
Gen 5 = 156
Gen 6 = 100 in XY, another 20 were added in ORAS
Gen 7 = 99

And before you say "b-but mega evolutions and alola variants don't count", they do. They have different designs, different stats and they require their own space of memory in the game's code. As far as the game is concerned, the difference between Alolan-Sandshrew and normal Sandshrew is the same as the difference between Alolan-Sandshrew and Weavile. The only difference is that they don't have a separate Pokedex slot. Forms are a slightly different case, some of them can be considered new Pokemon since they have completely different stats and appearances (Shaymin, Giratina, etc.) while others are purely cosmetic (Unown, Spinda, etc.). I didn't bother adding forms to the count above so some gens have an even higher number of new Pokemon than the one I listed.

If you don't want to count either of those as new Pokemon because they're not "truly original", then you should ignore all the cross-gen evolutions that gen 2 and 4 added. And don't forget that gen 3 had a bunch of paired Pokemon with similar designs to showcase the double battle feature (Plusle/Minun, Volbeat/Illumise, Latias/Latios, etc.). And gen 5 created a bunch of second/third-stage evolutions for the sole reason of padding out their dex, as well as designing a number of Pokemon that were callbacks to older Pokemon (Machop -> Timburr, Woobat -> Zubat, Tauros -> Bouffalant, etc.)

Also I posted the version for ants because the full-size version is too large to post.