oak umbra
[PSA] As of the current Patch 1.2.
The fight can randomly bug out and not spawn a platform, which makes it very hard to survive and you will have to time the jump; although it is possible, you have a very narrow window to go up and not land before the wave hits.
If you cannot get the jump itself to work, reset the fight and hope for the platform to spawn; alternatively, you can try setting details and render distance to Ultra to make sure they are rendered in range.
tough valley
Alternately, rogues and mages can teleport through the wave
full coyote
I remember beating this boss without realizing there was a platform because of how far it always spawned behind me lol.
If you're wondering about the time window to enter a geyser, it's roughly at the 2 seconds mark before the attack and glide towards boss.
coral wren
I haven't had any trouble with simply jumping on the geyser and hovering, any time close to 2.0s works