Rendolf

Are you playing the game modded? That would be the only way you'd be able to get Clodsire, since standard Reborn only goes up to gen 7 and Clodsire's from gen 9.

Should be just any of the places up the first Rock Climb section that Hardy shows you, on the way to the Glass Workstation. By any chance, were you only searching the area at night? If so then that would explain it, since Wigglytuff can only show up there during the morning or daytime (barring the Snivy Nest it seems).

You should be able to catch a Wigglytuff in the mountain part of Route 4, if you have Rock Climb (though I can't really think of a reason to try finishing the dex before you have Rock Climb anyway)

Are you sure you're at Blacksteam Factory and not Mosswater? Blacksteam is the one that's more to the northwest while Mosswater is the one by the border of Upper and Lower Peridot that you went into before fighting Julia.

They do in Reborn. There you get one for each new Z-Cell you collect.

Do you have the right code from the Subseven Sanctum? It should be

Kind of, it's the forums for a Pokémon fan game (or a few I guess). I would guess it came up because one of the characters probably said that number in the game at one point.

If you access the Fishing Pond in the southwestish and the Old Rod from one of the houses a bit further west you can catch a Goldeen with Lightning Rod which is pretty useful for all the Electric moves.

The lady with the sick husband is the one that's supposed to give you the Chespin Egg (down in 7th Street in the morning, I believe) in exchange for your Oddishweed. If you've already done that interaction are you sure you don't just have the Egg in your PC or something?

Reborn uses mostly Gen 7 breeding mechanics, and as far as I know that feature was removed in Gen 6.

I believe it's the reward from Bee in Agate City for showing her your Pokédex with over 300 entries in it.

It does say after obtaining Badge 2, so have you beaten Florinia yet? That's the only thing I can think of since I've never gotten Clamperl from that egg.

What Prankster technically does is increase the priority of a used status move by 1. So if you're not seeing a noticeable difference with Trick Room it's probably because it has a base priority of -7 (the lowest in the entire game actually), so Prankster only raises it to -6 (causing it to tie with Circle Throw, Dragon Tail, Roar, Whirlwind, and maybe Ally Switch but I don't remember how much the devs lowered it's priority by).

It should be one of the 7th Street purchasable Pokémon if you didn't save it in Blacksteam before restoration (though I think if you open the cage but don't bring it with you before restoration it might be gone for good)

Good in what sense? Bronzong itself is pretty good, and Levitate is probably it's best ability for non-PvP (unless you're fighting fire types or want to use Heavy Slam). The nature isn't great for Bronzong (Sassy, Careful, Brave, or Calm would be my recommendations depending on what you're running). The IVs are alright if you're running a defensive build that utilizes Gyro Ball or Trick Room (though in that case you'd definitely want to change your nature to either Sassy or Brave). The EVs are good for Special Defense but bad for everything else; I'd recommend that you should reset everything but Spec Def and HP using berries, max out HP, and give the last 6 to Defense, Attack, or Special Attack, depending on your moves. The item should probably be changed to Leftovers when you have them. If not then if you happen to be running all attacks you could go Assault Vest or if you're running Gyro Ball or Trick Room you could actually keep a Power Item on it if there are no better options. I can't comment on the moves since you didn't include them, but support ones are generally good since Bronzong's Attack stats aren't great.