Swonic

I literally went around the entire city and talked to people. Basically there are people in each area and I don't remember which ones exactly want to go. Just toggle superspeed with alt and talk to everyone while holding x so it bypasses their dialogue. You know they went to help if they disappear after talking to them

Spoiler alert.

Sweep the left side of the Railnet. There will be a metal barrier you need to open.

How do I open that

Redirect the rail tracks so that they lead to it.

hint: It's NOT the Wasteland.

All three of them are in locations that make sense for them, so if you think about where you'd expect them to hang out, you should be able to figure it out quickly c: ...And I suppose it sort of encourages people to explore the city a bit?

Skuntank can be found in Ametrine Mountain, or one of the other mountains. You're going to need Surf and Waterfall, and it's at a high level of 68.

of the 6 pokemon, Croagunk and Nidorina are the only ones that can be 'found'. Skrelp is obtainable from the coral ward with a good rod. Zubats/Golbats are found in the railnet where the track puzzle is. Haunter is dead, don't ask, he was axed with a spectral axe 5000 years ago (damn you ame ;-, and trubbish and grimer can be found in any sewer/alleyway you can think of.

or whichever one of trubbish/grimer was on his team - I forget.

its in coreys room in his gym

You can get it in Corey's room when you get your third badge I think.

After Corey jumps off Beryl Bridge, you can grab it from his room.