Talen Horton-Tucker had a pretty nice looking shot, it was his shot selection that was an issue at times. Wigginton's shot was very nice. Jackson and Grill both have a few things to work on (Grill's feet especially), but their shots are nice overall. Solo and Conditt both have good looking shots, but Conditt needs to actually have confidence in it. Even Lewis has a good looking shot but mentally he doesn't know when to shoot, when not to shoot, and his defense takes him off the floor.
Halliburton has probably had that form since he was little and either his father or high school coaches decided they were not going to fix it. Or, maybe they tried to fix it but Tyrese didn't want to change it because it was effective. His form is always going to look like that because he's been using it for all of his life. It'd be impossible for Prohm or any coach to be able to completely change it, rather they can only give him little tips to help out (like not dipping the ball as much).
And if you were to look back at Matt's freshman and sophomore years, you'd see a big difference in his feet when shooting. He constantly was kicking out his legs, wasn't completely getting square, etc. I have no idea if that was Prohm or if he made the adjustment himself, but his footwork got incredibly better and his shot got more consistent as well.