Yeah, Black Panther is most definitely not street level. In classic stories he ate a herb that gave him enhanced senses, speed and the like, but after 2012 or so, he got a permanent upgrade. Bast, the deity which protects Wakanda, made him "King of the Dead", which means he now posesses the memories of all previous Panther and can talk to them in the astral plane. Plus, he got strentgh, speed, etc, etc upgrades. Besides, Wakanda is the most advanced nation on earth, so he's got some serious gear. Vibranium Microweave, Kimoyo, etc, etc. He's Batman + Iron Man + Captain America. Honestly, he's "street level" in the way Ghost Rider and Spider-Man are.
As for his feats, well, he's got tons and did beat up Tony during Civil War, but some are PIS. The Silver Surfer for one in that Fantastic Four arc was purely illogical and one of the most WTF scenes. Doom, he didn't really beat, as he had Storm with him, were in an enclosed space, and Doom just stopped the fight. Honestly, good as T'Challa is, and he's goood, Doom is on a whole other level. He's Batman + Iron Man + Doctor Strange. Doom could beat anyone with anything, he's just that good. As for Mephisto, T'Challa outsmarted him, which was damn bad-ass, back in the first issues of the Priest run.