1st scenario, Kakashi wins easy clap. No explanation needed. Kakashi p1 was a near prime vet, battle hardened and absurd IQ. Sound four were cocky little teens because they knew they were stronger than everyone in their age group. Kakashi was shown to have 3 tomoe, chidori, high IQ, superb water techs, and extreme CQC capabilities. Also a decently high chakra reserve. Kakashi would dismantle and wash those one trick ponies. Only one that would remotely stand a chance is Tayuya with her sound techs. Their curse marks also did little to nothing but slightly boost their techs. Mind you All the genin sent out at that time were all able to overcome the sound four. Even Choji solo'd... Easy clap... Don't disrespect an OG like Kakashi like that.
2nd scenario, Kakashi wins Mid diff. This one is a little harder to explain because he was the OP ally of sound four/five. His CM actually gave him a speed boost and boosted his already amazing techniques. However I think Kakashi still wins mid diff based off of IQ and experience. It would be a good fight. I also don't think CM Kimi could blitz Kakashi. Kakashi was shown to be pretty fast and also copy pretty much everyone he came into contact with in p1 with 3 tomoe. So I don't see why Kimimaro would be an exception to this.