Examples of simultaneous ability use

Peter Petrelli, whilst training with Claude, uses telekinesis while the two are both using their ability of invisibility.
(Unexpected)

Future Sylar, appearing as Nathan, creates an illusion while telekinetically cutting through Claire's skull.
(Five Years Gone)

Future Peter uses telekinesis while invisible.
(Five Years Gone)

Future Sylar creates an illusion and phases Future Peter through a door.
(Five Years Gone)

Sylar freezes water to make snow while also using telekinesis on his mother's snow globes.
(The Hard Part)

Peter regenerates...

...while telekinetically pinning Will to a wall.
(Kindred)

While time is stopped, Peter creates lightning.
(Truth & Consequences)

Linda Tavara sees spirits and a nurse's aura at the same time.
(Moonlight Serenade)

Future Peter stops time and removes Peter from Jesse's body.
(One of Us, One of Them)

Future Peter uses a trio of abilities simultaneously: telekinesis, regeneration, and illusion.
(Resistance)

Arthur flings Ando away while erasing Hiro's memories.
(It's Coming)

Sylar holds a bullet immobile while using lie detection.
(Our Father)

Sylar uses telekinesis and lie detection on Angela to determine that she knows who his real parents are.
(Dual)

Sylar uses telekinesis and lie detection on Luke Campbell.
(Trust and Blood)

While shifting from Agent Donner's form...

...to his own normal form, Sylar regenerates.
(Turn and Face the Strange)