Naclstack is a pure Rock type, and is the evolution of Nacli. To start things off, I don't mind the design of Naclstack, but I could see it not appeal to some others since it's basically just a pile of rocks with some salt added. However, Naclstack I'd say is alright to use in battles, especially when holding eviolite to boost its defenses. Although, it does still get outclassed greatly by its evolution, Naclstack does still have some alright stats, mainly its base defense being the best, then learns some alright moves, and has alright abilities. Overall, Naclstack is a fine middle evolution, but I think when comparing it to all the other middle evolutions of Paldea, it doesn't really have as great of a stand out factor.