EDIT: this version is now out of date! You can find the latest version of Pinball Generations by clicking here
A small update has been issued for Pokémon Pinball Generations, addressing an issue where Kingdra was unobtainable.
You can get the game right here: https://rainbowdevs.com/title/pinball/
Or find it on PokéCommunity here: https://www.pokecommunity.com/showthread.php?t=417346