Toxapex is an extremely common Dragapult partner for good reason, acting as an excellent defensive pivot and status spreader/knock utility to complement Dragapults high speed. However, I don't think that Toxic Spikes is a good option in the current metagame between the abundance of HDB and Amoonguss/Pex—you're realistically never going to net a poison on a relevant target by using it (not even Clef). Scald/Knock+Toxic is just far more consistent at the whole status spreading thing, which is what you seem to be selling as an advantage of TSpikes on Pult teams. If you do still run TSpikes, I feel like you either need to carry Knock yourself or pair with a Pokemon that can Knock Off Blissey's boots, as it is is one of the few targets that TSpikes actually serves to keep poisoned long-term.
Magnezone+Dragapult is a core I've used a few times and I don't really think the set listed complements Dragapult very well when compared to Choice Specs. The ability to just maul Clef+Pex+Corv/Buzz/Skarm builds that lack Blissey is just a very good selling point of Zone when paired with Pult, and Iron Defense sets just feel kinda tepid in that role due to just how much firepower is being sacrificed to do it. Sure, you can trap Excadrill and have Body Press to better pressure Blissey, but you're not a long-term response to Blissey by any stretch and there are still 4 other slots to cover or otherwise overwhelm it regardless.
I don't have any concerns with Craw; it's a very simple mon that pairs well with Pult, though not one I tend to use due to my playstyle (I know Tyson likes it tho).
Weezing once again just has the issue of TSpikes not being very good in the current meta. I also find slashing Will-O with another move somewhat questionable—if you needed to mention TSpikes, I think you should've slashed it with Aroma rather than slashing Wisp with Aroma—though once again I think something like Sludge+Wisp+Split+Aroma/Toxic would be better than TSpikes wrt consistent status spreading.
My gut tells me CB Urshi is better with Pult but I must confess that I've not used BU Urshi enough to really justify that claim. One thing worth noting with it is that it just doesn't pressure Clef all that well compared to CB—you'll need to work extremely hard to not just be used as Soft-Boiled fodder if the aim is to chip it down into boosted Hex range, which is compounded by the LO recoil, although the flipside is that u pressure Mandi far better than you would otherwise. Regardless Urshi+Pult is good so it's whatever lol.
Shift Gear Toxtricity is another straight forward partner; pressures Blissey in a way that other special wallbreakers can't and mauls teams that rely on Pex pivoting to counteract Urshifu.
