It's not that I dislike the Pleasantview NPC but I don't want to fill all of my neighborhoods with those PV townies.
I would like to have the ones from Strangetown instead.

Tarlia's version doesn't contain any townies, so I assume, I'll have to use EA's Strangetown... but I know that EA's Strangetown is heavily corrupted.
So, does it copy the corruption while the game is adding the townies/NPCs?

Or is it corruption-free then?

It only copies the townies files over and there brand new sims again, there should not be the org. corruption from Strangetown when you do it. Only the playable sims are heavily corrupted.

You will have to renumber Strangetown to N001 for this to work.

You could instead get the game to generate a whole new bunch of townies in an empty hood. That way they're different every time.

All you'd have to do was go into Program Files\The Sims 2\TSData\Res\UserData\Neighborhoods, disable the N001 folder (just changing the name works), and rename the N002 folder - and all of the files inside - to N001. Maxis Strangetown is heavily borked, but townies start with a clean slate when recreated by the game. I use Bulk Rename Utility for stuff like that, but there's a lot of programs that will do it in a snap!

If you'd like to attach them to an existing hood, I think making a new hood with the ST townies, converting it into a subhood, adding it and then deleting it should do the trick?

A number of days ago, downloaded a program that checks a neighborhood for signs of corruption. some day between then and now, ran that program with the base game neighborhood; all 3 showed signs.

yet the signs seemed to not affect Townies & NPCs.

I think a more reliable test would be to create a 3 new 'hoods: one with Pleasantview's townies, one with Strangetown's townies, and one with Veronaville's townies. Then, without adding any new sims or lots or otherwise changing things, run Hoodchecker on each new 'hood. That will show what corruption actually crosses over into new 'hoods with the townies/NPCs.

I've just tried it out. It added all of the NPCs/townies but there were way too many SimDNA files after checking it in SimPE. There were about 310 SimDNA files and I went checking in Strangetown, the number of SimDNA files is also about 310...

So the game copied all of the SimDNA files into my neighborhood.

I didn't know it would do that! I wish I had the technical knowledge to make cleaned up versions of the templates with townies but without the extra SimDNA!

And also, do they contain extra IDs as well? I can't remember the name of the IDs that can attach to new/born in game sims but if there are loose IDs around, they can attach to born-in-game sims. That's why some toddlers in corrupt games have aspirations besides Grow Up, and wants to make money and woohoo and other things they shouldn't want to do. If anyone knows the name of these IDs (we talked about it in the signs of hood corruption thread) let me know and I will edit my post. Thanks!

EDIT: Did you make the other 2 test hoods as well? If you did, check the number of SimDNA files there and compare it to their main hood equivalents (like a custom hood on PV's template to vanilla PV.) I'm curious if this is a ST-exclusive problem or applies to all the premade hoods/templates.

I've just tried it out. It's not unique to Strangetown.

It also happens if you use Pleasantview as a template. There are too many SimDNA files.

Ok. I have an idea:

1. Create a 'hood using the template you want. Don't worry about SimDNA, this is a temporary hood.
2. Go into SimPE.
3. For each EA townie/NPC you want, write down their skills, personality, aspiration, LTW, and career unless you want to reassign it.
4. Export those townies' appearances using Sim Surgery in SimPE.
5. If you want townies from different templates in the same hood, you can create more temporary hoods with the other templates and repeat these steps.

To make the 'real' hood: (you will need Sim Blender or a similar mod)
1. Put in totally clean and empty templates.
2. Make a hood like normal.
3. Recreate the sims whose appearances you extracted in Body Shop. Set their personality, turn ons/offs (which even with normal templates would be random and different in each hood anyway), and aspiration. Even if you make them all in one household and they must share a family name or be related to older sims (like kids and teens), it's ok. That and the rest can be fixed in game.
4. Turn testingcheats on IN NEIGHBORHOOD VIEW! Doing it before loading the townies' lot is CRITICAL!
5. Move them into a lot.
6. One by one, use testingcheats to drag up or down their skills, personality, relationships, etc. can't do this? Go back to step 4. You probably turned testingcheats on in lot view instead of neighborhood view.
7. Use sim blender to reroll their LTWs, change aspirations, change names, remove family ties, or make any other needed changes.
8. Use Sim Blender's built in teleporter to make the sims townies or downtownies.

I like this plan because you can mix townies from different templates and edit them as much as you like without corrupting your new hood. I haven't tried it because I don't do maxis townies, though.

OK, the townies are not a problem. It's possible to generate all NPCs at once, so I could use the mailbox to generate the NPCs and then use SimSurgery to replace their appearances.

But for the final step, you have to change the appearances of the sims you've changed using SimSurgery. For most of the NPCs, it's not a problem but how about Repo Men, Social Workers, and such NPCs?
I read you shouldn't mess with them in any way or form but can I still do it? Because, it's just a throw-away neighborhood and the game doesn't copy neighborhood corruption over. So, my new neighborhood won't be corrupted, or?

Well, I've done it. Not seen any problems with Moo's hoodchecker. It's just the appearance, not the sim data. The no-name NPCs (and drivers) who aren't universals have files in your neighbourhood folder so changing them can't affect your game. It's only the universal NPCs where there is only one file tucked away in the game files that changing them borks the lot. If you do have a problem, deleting the neighbourhood in this case should fix it. I'm not sure how far no-name NPCs would cause corruption. The reason you are not supposed to interact with them is that they are hard coded to certain behaviours and won't do anything else. Trying to get them to interact in other ways or be playable or making them selectable (for any length of time) causes problems but I would think it is only with that particular sim rather than being the creeping problem type of corruption. Making them playable just means the sim in question can't do anything - you click on stuff or other sims and there are no options.

I wouldn't bother with no-name NPCs just to be safe. They get randomized in every 'hood anyway.

I have a mod that can change the sims' appearance without making the sims playable at all but I have to summon them first using Teleporter Scrub.

Would summoning them and then changing their appearance corrupt the neighborhood?

I don't think so Jawusa but it might be worth testsing.