A Gen 7 Buff (like a Gen 6 Buff) is a stat buff change to Pokemon from Gens 1-5. It could also mean new moves that a Pokemon can now learn in Gen 7 (such as Mantine now being able to learn Roost and Flygon now being able to learn Dragon Dance), but that doesn’t translate into Pokemon GO.

Here are the links that show the Gen 6 and Gen 7 stat changes:

http://www.serebii.net/xy/updatedstats.shtml

http://www.serebii.net/sunmoon/updatedstats.shtml

Are Gen 7 Buffed Stats Applied To Pokemon GO Yet?

Unfortunately, no. Niantic’s still using Gen 6 stats so far. Anyways, here’s if Gen 7 Stats Were Applied To Gen 1 (No Alolan Forms) and Gen 2 for Pokemon GO:

 PokemonGenAttackDefenseStaminaOld CPNew CP (Gen 7)
Arbok11851581201,7371,908
Dugtrio1205147701,3331,612
Farfetch’d11671181041,0921,430
Dodrio12231481202,1382,205
Electrode11761821201,9001,945
Exeggutor12331611902,9162,945
Noctowl21611792002,0402,245
Ariados21611301401,6361,700
Qwilfish21841661301,9102,013
Magcargo21552091201,5431,857
Corsola21181751301,2141,378
Mantine21482601702,0322,310

How’ You Find The Supposedly New CP For Pokemon GO?

I used this formula to find the Gen 7 buffed stats of Pokemon. (discovered by /u/CustomOndo)

Wouldn’t They Apply Them Only When Gen 7 Actually Comes Out?

Now this is the kind of confusion that I’ve heard from some people. Anyways, if Niantic had already applied Gen 6 stat buffs to Pokemon GO (even though only Pokemon from Gens 1 and 2 are out), then why wouldn’t they apply Gen 7 stat buffs? But maybe it’s to come with the gym rework. Who knows?

So yeah. Hope this helps you to understand about what a Gen 7 stat buff is and how it’d affect Pokemon GO. (can’t do a good outro, as always. :P)