This isn't DMS Kakashi just in case. Kakashi's kamui pre DMS is pretty much useless, his aim was terrible he wouldn't risk losing his consciousness over a kamui that might or might not hit, against a guy who has 15 times his chakra reserves. The difference in chakra is too big for Kakashi to do anything.
Kakashi doesn't need DMS to beat Kisame. Chakra reserves don't matter if you don't have good enough counters for your enemy's abilities. 4th Raikage's chakra pool is as high as that of a Bijju but he apparently couldn't best Minato even with Bee's help. His Kamui was only bad at the beginning of the Shippuden. He got better over time and he's using it almost on par with Obito in the war.
They don't beat pain, Itachi genjutsus Minato into the next world. Genjutsu is more broken than these.
Tobi has teleportation too besides his different jutsu arsenal, plus the fact that he was equal to MS Izuna. Obito is far more broken tho, I always had trouble picturing him fight. He was severely nerfed by Kishi against Minato, was young too.
They both beat Pain. They can virtually counter every single ability in their arsenal. Obito would beat them rather easily compared to Minato because of Kamui. Minato is more than smart enough to avoid genjutsu; he grew up with the Uchihas, and he's not an arrogant prick, unlike Orochimaru. Even someone as bold as 4th Raikage wasn't falling for Genjutsu against Sasuke when he was paying attention.
Minto is also a sensory type, so he can sense the chakra building up in the eyes and act accordingly. Obito's genjutsu was good enough to control Kyubi and a perfect Jinchuriki but the dude didn't even attempt it against Minato. He wasn't nerfed against Minato. Minato is simply faster, which is what matters the most in a battle b/w teleportation users, while Obito has a much better ability.