Looks like I missed a few unused Sims. Here we have two unused Sims households (never mind the picture; it's just for posting). It's the ep3test and Pinku households! All of them were generated using an old version of the game. Like the Pond, Powers, and Riviera households the ep3test household was spawned by replacing all the other households with the xml found in the one in question. Eventually the right configuration came out. After that I had to rename the same since they spawned without names. In the current version of the game they do spawn with names (yeah, I don't know why) so I used that as a reference for the old version and got our three new friends - Joel Meadows, Andy Campbells, and Iko Yono - out from obscurity. Their traits are undefined, but the aspirations aren't. I just went for whatever random ones the game generated. Also, these Sims are pre-Seasons, so they lack those outfits entirely.
Pinku is a different story. She can't be found using Sims4Studio. If you go into the delta folder and then in ep03 you'll find several packages. We're looking at ClientDeltaBuild0. That's where the households for City Living are found. This isn't the case everywhere - it's annoyingly inconsistent! Anyway you can see the unused and totally unloaded Sim here. Surprisingly her first and last name are listed and can be looked up in the String Table. She's Penny Pizzazz! An early version? Or maybe she started out as Penny? No clue! Unlike ep3test all her traits are defined. Of course she's pre-Seasons too. To load her I deleted the Pizzazz household template and copied her instance into Pinku's. When I started a new game it spawned Pinku. Easy, right?
All of them have outfits that have more than just the basegame and City Living referenced, so like the other unused Sims I doubt they were ever meant for the game proper.