Ah found my mail. Please keep in mind that this is my opinion and my arguments. You're ofc allowed to disagree

"As the generations go, I believe there is no clear idea at which generation we are right now. As far as we know Hasbro doesn’t categorize their toys in generations.
The other thing that doesn’t help is that not everyone has the same idea about the generation order as well. Some of them for example claim that the Vintage Kenner ones from the 90s are actually generation 1 and that the 2005 ones from Hasbro are already Generation 2. Some also claim that generation 2 and 3 are the same but that means that G2 contains over 2300 pets. Also the G2 and G3 ones are quite different with the use of Eye-Symbols as well as the brand-design. A thing we also keep in mind is that everyone is able to edit Wikipedia. So for me it’s more a personal thing, that everyone has their own idea of which pets belong in which generation. I’ve written down my theories below:

G1 – The Start of Hasbro’s LPS line, pets are natural looking in terms of colors.
G2 – Introduction of the eye-symbols
G3 – Pets become more cartoon-like in terms of colors and expressions
G4 – Complete reboot in terms of pet-design and packaging, also ties in with the show
G5 – New pet-design as well as well as the packaging
Pet In the City – A smaller line that falls under G5, Counting restarts at #1
G5,5 – Counting starts again but thing in terms of packaging and logo are quite similar to G5
G6 – Pets are the same as G5,5. But there’s a total new way of counting pets (Series 1… *number) etc. Packaging and Logo have also drastically changed."