Yes they are trained and capable but against Sidious? They die plain and simple, nothing they can do to win or match Sidious for very long. Sec i'll try and find some stuff on Sidious to show.
Edit: Ok here is some stuff...
His lighting powerful enough to reduce a Sithspawn to ash.
Burning 3 dark side prophets to ash with lighting.
Lightning blasted the clouds above, and lightning blasted from Palpatine's hands, and Mace didn't have time to comprehend what Palpatine was talking about; he had time only to slip back into Vaapad and angle his blade to catch the forking arcs of pure, dazzling hatred that clawed toward him. Because Vaapad is more than a fighting style. It is a state of mind: a channel for darkness. Power passed into him and out again without touching him. And the circuit completed itself: the lightning reflected back to its source.
Palpatine still made no move to defend himself from Skywalker; instead he ramped up the lightning bursting from his hands, bending the fountain of Mace's blade back toward the Korun Master's face.
Mace's blade bent so close to his face that he was choking on ozone. "Anakin, he's too strong for me—"
This was beyond Vaapad; he had no strength left to fight against his own blade.
Mace's blade was BENDING
from Sidious's lighting.
Maul had not wanted to disappoint his Master. He wanted to apologize and ask for forgiveness, but he knew if he did, his punishment would be even worse. And then he thought of how long he had suffered on Orsis because he had not been allowed to use his powers, and he felt his shame transform into rage. He looked up at Sidious and was about to speak but his Master made a pinching gesture. Maul felt his throat constrict. Sidious walked a few steps away from Maul before he released his remote grip on Maul's throat.
Using Force Choke on Maul.
Suddenly, my lightsaber is gone. It flies from my hand across the room. It lands in the hand of my Master. I never see him enter. Not if he doesn't want me to. The smile of triumph fades from my face.
Pulls Maul's saber away.
In the inner recesses of his private office, the Jedi confronted the Chancellor. Palpatine produced a lightsaber hidden in his sleeve and let the dark side flow through him. It granted him unnatural dexterity and speed—enough to quickly kill three Jedi Masters and force the mighty Mace Windu back.
Ok i'll stop now, theres so much I could post but then it would be such a long post to read.