Oasis mogs, vastly higher AP (minus Diego's slicing, but Secco could unironically probably cripple with just his blows alone), potentially better speed, better AOE, etc. Diego can incap and instant win if he gets one cut on him via virus, but given Secco's attack method via popping in and out of the underground and also having contact based wincons, he's far more likely to get it off plus Secco wears a Stand suit which makes infecting him even harder. Diego is way more skilled and intelligent, but when your foe just camps underground and the only wya you can hit him is getting within his kill range, which he beats you out on, you kinda ******.
That one's tough, but mostly because both literally pull powers out the ass all the time, and Gyro def has powers he just hasn't used. Could go either way depending on who does what and when they do it.
Probably highway star, Bruno can't really do anything there, he vastly outclasses Yuyu in every stat, but he can't really win as he can't touch HS to beat the **** out of it, because mere contact with it proc's the nutrient absorption. And while Bruno through will alone might be able to attack a bit anyway and zipper him up, that wont matter against a foe that disassembles itself anyway, and taking out one or two feet don't kill the Stand or stop the rest. Bruno could win if Yuuya himself starts within like 10m~ of Bruno, because Bruno would just zipper punchy and blitz him to death, but if Yuuya starts off further, Bruno is ****** because he can't actually fight the Stand despite eclipsing it.
If it's raining, Blackmore wins so fast it isn't even a fight. If it isn't raining, they win so fast it isn't even a fight, assuming distance like that in the arc.
Sandman, has hilariously better range, can do hundreds of attacks at once, with every attack being lethal. While Koichi has to get within 5m of him, and actually attack Sandman. Koichi doesn't have much of a chance getting within 5m before getting hit by one of dozen attacks.
If they start off 5m away though, Koichi wins everytime, but any notable distance and het gets memed on.
Speed equal kinda ***** over the short-distance fast Stands when put up against long range dudes.