He'd have good chances against Manuwa, Glover and Rumble. Less so Rumble than Glover and Manuwa, largely just cuz' of his power and reach, but still, a good chance. Counter-strikers with good movement always have good chances against aggressive power strikers, especially if they have somewhat-limited striking like Glover. Machida got his title shot off of people like that (including guys with better striking than Glover, like Thiago Silva), and he did it against a great striker like Gegard Mousasi, too.
Gustafsson's height makes him a little more difficult. People have been underrating Gustafsson since he struggled with Blachowicz for some reason, though; it's like people thought Jan was a bad fighter so Gustafsson not finishing him is horrible, but he's not and it's not.
Because of his height and his long legs, and because Gus knows how to distance himself against shorter fighters, it'd be a little harder to get a lot going for Machida. Circling counter-strikers have a historical tendency to struggle against taller fighters that know distance.
Cormier's wrasslin' gives him a big advantage, so he'd have a lower chance against him than any of the others, but it's not like Machida's an easy guy to take down. His movement and
Karaté- and Jūdo balance made him very tough to get a deep shoot against and to get a good grip in a clinch. He'd have a better chance than people give him credit for because of that.
Nothing fucks up a fighters career like confidence.
I know. Just look at Mcgregor's career.
It's sport's psychology 101. Confidence is athletic cancer.