OP, I think VGChartz is the wrong place to ask this question. See here, there is someone that says Switch 1 is 9th gen because it's listed on the main page, but at the same time says the switch 2 is a 10'th generation console, even though it's still listed under 9th gen consoles on the front page. I tried asking trunks (site admin) if the Switch 2 will be added to the PS6 10th gen console section once the PS6 releases but I got no reply. We really need an answer to the question" Why is Switch 2 listed as a 9th gen console on VGChartz" to debate this here. It's inconsistent. How can Switch 1 and 2 launch over 8 years apart and still be in the same generation according to the admins of this website. 

The console gen term has less meaning now than it used to. But I have a check list with criteria I go through, if I want to determine which gen it belongs to:
In terms of horse power, which gen is it closest to: 7th gen
In terms of technology overall, which gen is it closest to: Tegra X1 is 2015 tech, so newer than 8th gen competitors, but not by much: 8th gen
Of competing systems, which launch dates is it closer to: 8th gen
Which gen of systems was it intended to compete against: Debatable, but probably 8th gen
Which gen of systems did it end up sharing most of its lifetime with: 9th gen
In terms of multiplats, which gen did it share most games with: 8th gen

The Switch is therefore an 8th gen system.

As for Switch 2 however:
In terms of horse power, which gen is it closest to: A bit more convoluted because of mid-gen upgrades, but looking at base console it is probably right between 8th and 9th.
In terms of technology overall, which gen is it closest to: Nvidia made a new costum chip, so 2025 tech: 10th gen
Of competing systems, which launch dates is it closer to: Seems PS6 and a new Xbox is not so far in the future, so 10th gen
Which gen of systems was it intended to compete against: Debatable, but probably 10th gen
Which gen of systems did it end up sharing most of its lifetime with: Hard to guess, but 10th gen seems more likely

Which puts Nintendo in the weird situation of having two 8th gen systems, a 10th gen system, but no 9th gen system. Then again they also had a 1st gen system, but none in the 2nd gen before releasing the NES in the 3rd gen.

I would say historical precedent can go both ways; there's precedent for instance for a "midway" console being seen as kicking off the next gen (Dreamcast) and being part of the current gen. (Colecovision)

The console gen term has less meaning now than it used to. But I have a check list with criteria I go through, if I want to determine which gen it belongs to:
In terms of horse power, which gen is it closest to: 7th gen
In terms of technology overall, which gen is it closest to: Tegra X1 is 2015 tech, so newer than 8th gen competitors, but not by much: 8th gen
Of competing systems, which launch dates is it closer to: 8th gen
Which gen of systems was it intended to compete against: Debatable, but probably 8th gen
Which gen of systems did it end up sharing most of its lifetime with: 9th gen
In terms of multiplats, which gen did it share most games with: 8th gen

The Switch is therefore an 8th gen system.

As for Switch 2 however:
In terms of horse power, which gen is it closest to: A bit more convoluted because of mid-gen upgrades, but looking at base console it is probably right between 8th and 9th.
In terms of technology overall, which gen is it closest to: Nvidia made a new costum chip, so 2025 tech: 10th gen
Of competing systems, which launch dates is it closer to: Seems PS6 and a new Xbox is not so far in the future, so 10th gen
Which gen of systems was it intended to compete against: Debatable, but probably 10th gen
Which gen of systems did it end up sharing most of its lifetime with: Hard to guess, but 10th gen seems more likely

Which puts Nintendo in the weird situation of having two 8th gen systems, a 10th gen system, but no 9th gen system. Then again they also had a 1st gen system, but none in the 2nd gen before releasing the NES in the 3rd gen.

The site Admins could have easily created a new section on the front page for the Switch 2/10th gen platforms, so why didn't they for Switch 2? If practically everyone on VGChartz believes the switch 2 is a 10'th gen console, why isn't there more interest in getting an answer as to why it's listed as a 9th on the front page. 

The site Admins could have easily created a new section on the front page for the Switch 2/10th gen platforms, so why didn't they for Switch 2? If practically everyone on VGChartz believes the switch 2 is a 10'th gen console, why isn't there more interest in getting an answer as to why it's listed as a 9th on the front page.