Install Instructions Warning:DON'T put these into TS2, these neighborhood are NOT meant to play in TS2. Instead, download recreated versions of the Sims Stories neighborhoods if you intend to play these neighborhoods in TS2.
While technicially, these neighborhoods CAN be imported into TS2 if you have The Sims 2 Pets EP installed, BUT, it doesn't mean that the neighborhoods are free from corruption then.
There's a NPC controller data (dog show judge) which doesn't exist in TS2. So, importing a Pet Stories neighborhood into TS2 clashes with the NPC controllers, since in TS2, the NPC type number used for dog show judges is used for another NPC (I think housekeeper NPC). And even if you only have all EPs up to Pets but nothing more, there'd still be a missing instance for NPC controllers which could cause corruption.
Which is why you should download recreated neighborhoods for TS2. Garden Heights is available, Mesa Flats and Arbor Falls are still in the works... but soon available as well.
Non-Default Replacement Versions
Cut and paste PS01, PS02 and PS03 to
C:\Program Files (x86)\Electronic Arts\The Sims Pet Stories\TSData\Res\UserData\Neighborhoods
Documents\Electronic Arts\The Sims Pet Stories\Neighborhoods
Note: You have to play through the story in order to unlock the story rewards, which is why, I didn't do a default replacement version.