I think Appel and Thompson are still perfectly fine as the 6th guy in a trade, especially for a team that just needs major league players. They both still have potential and they both could still pitch (albeit, badly) in the majors tomorrow. But the Marlins may not want guys like Joseph and Hernandez, if the Phillies don't see them as cornerstone players in 2-3 years that's going to be even more true for the Marlins. They are more useful to a win-now club. (Plus Hernandez, while controlled, isn't cheap, or won't be after next season).
For Ozuna they are going to want 2-3 top prospects. In other words, not Joseph and Hernandez, Hoskins and Kingery. Stanton would presumably cost less talent because it's not like the Marlins are going to pay salary. But he'd cost.