Jutsus he copied with the Sharingan, Raikiri was said to be his only original jutsu by, Gai in part 1. No Sharingan means he can't read and predict his opponent moves and he heavily relied on that for tough foes. Gaara was fighting his Edo dad then helped Oonoki with Edo Muu then took on Edo 2nd Mizukage; after that he helped against Edo Madara for a bit before the other Kages came, got healed up and went on taking on 5 Susanoo's while helping Mei. Gaara would destroy Kakashi, the fact that Gaara can fly and his sand is capable of tanking C3 (Tbb level explosion), 5 Susanoo blades from Edo Madara, and Sasuke's Enton spikes; nothing Kakashi has is getting through Gaara's defense. Sure Kakashi is smart, more experienced, and more skilled in certain fields but what does that get him when Gaara flies high up, turn the battle field into a dessert and sand coffin Kakashi?
Mei can keep Kakashi away with boiling mist. She has earth, water, fire, lava, and boiling element while Kakashi has wind/water/fire/earth/ and lightning. Kakashi stated himself that his singular element jutsus are not a match against multi-element jutsus back when he used fire to try and block Kakuza's fire+wind. Mei also have more chakra than him and can use hidden mist more effectively as it was created in her village and she used it against Edo Madara.
Kakashi spent too many years mastering the Sharingan than on his own skills. He spent time learning many elements so he can make use of the Sharingan as his nickname is Kakashi of the Sharingan or copy ninja. He said himself he let his skills lower back in part 1; we see him get stronger base wise in shippuden but he's barely at Kage level in base. Naruto's base is Kage level of above that in the Last, 2 years after ch. 699.