If anything, this reduction would come as stages. -2 if weak to Grass, -1 if neutral, 0 if resisted, and maybe +1 if a Grass-type.
I'm okay with this, as it's not a SR clone as so many people suggest and think would be not only a good idea, but something Game Freak would actually do.
Ahh yes, that would be a good idea. I think it would be a really powerful move in its own right.
I also love the variety of Pokemon that we've seen so far:
Grass: Tsutaja, Shikijika, Kurumiru, Yanappu
Fire: Pokabu, Hihidaruma, Victini, Reshiram
Water: Mijumaru, Mamanbou, Swana
Normal: Chillarmy, Mamepato, Minezumi, Miruhoggu, Wooguru
Psychic: Munna, Musharna, Rankurusu, Gochiruzeru, Koromori, Victini
Steel: Gear
Flying: Mamepato, Koromori, Wooguru, Emonga, Swana
Electric: Shimama, Emonga, Zekrom
Ground: Meguroko, Moguryu
Dark: Meguroko, Zorua, Zoroark
Dragon: Kibago, Reshiram, Zekrom
Rock: Gigaiasu
Bug: Kurumiru
I mean, I usually like to have a Flying, Water, Fire, and Grass Pokemon on my team. Just from this list I know it is already possible.