I would vouch for all 4 changes.
Vap is a straight forward change imo. It's probably a top 3-5 offensive threat.
Zam is just as straight forward, been saying it for years. No top player would use zam other than to gimmick.
Porygon2 is so good on paper, and wildly mediocre in practice. Inexplicable tbh. I think Muk puts in a stronger case to be OU than Pgon2.
Dnite's move doesn't make a lot of sense if you compare it to the likes of Zapdos or Snorlax, but when you put it next to other "niche" players like Missy, Umbreon, Jolteon and even Blissey to a lesser extent, it makes a lot more sense. Dragonite's main difference is that the other "niche" pokes are the best of an unpopular role (except blissey; nothing blocks spin better than missy, nothing bps agi like jolt, and umbreon is umbreon), whereas dragonite is merely average but in a more popular role.