Since shadowless packs don’t have 1st ed stamps, are the weights on those typically lower? Meaning it’s easier to have a “heavy” shadowless booster pack at the same weight compared to 1st ed?
Is this a serious question? If so, no.
Super light, they don’t even have ink for the shadows!
You also need to be aware of which sets have Pokemon with longer average names, because the extra letters in the name will use more ink and thus be heavier.
Sets with higher set numbers into the triple digits will also use 33% more ink on the Pokemon card number system than sets with 2 digit cards.
I can see why you’d wonder this given the minute weight differences between such light products we’re talking about here, but it wouldn’t make a meaningful difference. What really stands out is the weight of a holo versus the weight of a normal card so you’re ever comparing between these two points. Every set is different, but generally 20g+ is likely to be a holo for vintage sets. The extra ink from a stamp isn’t enough to make a difference to that threshold.
1st edition has all the heavy hitters so its naturally more heavy