>>59028662Gen 1 got first dibs on a lot of very common animals.
Gen 2 and 3 also got a lot of first dibs as well.
Gen 4 was weird since there were a lot of connections to previous Pokemon in the form of pre-evos and evos.
Then came gen 5 and its soft reboot and a lot of new pokemon retread what we already had. Roggenrolla line replacing geodude, woobat line replacing zubat, purrloin/meowth, audino/chansey, timburr/machop, tympole/poliwag, etc etc etc
And then beyond that we start having a backlog of 600+ pokemon designs and inevitably things start getting repetitive.
I'm not saying every new gen is full of stinkers but when you go into gen 6 or 7 or 8 and we have fairly standard things like the regional rodent, the pikaclone, the regional bird, etc etc.
The newer gens just feel a lot more standardized compared to the earlier gens. Following a standard isn't a good way of making something iconic.