Psionic characters must have an aspect that describes the source of their mental powers. For example:
Traumatised Psi-ops Veteran
From there on out it's stunts. If you have a psionic aspect but no psi stunts then you are a latent and may may manifest your powers in the fullness of time. Latents may experience or display phenomena based on their aspect(s) but are unable to actively utilise psi powers directly under their control.
ESP: Extra Sensory Perception is one of the more common psi abilities and also one of the most useful. This stunt allows you to use Notice to observe things beyond the range of the five mundane senses. For example you could use ESP to detect the presence of someone behind a closed door, to "hear" the thoughts of others or to find a needle in a haystack. Each use of ESP requires a fate point.
Mindstorm: With this stunt you can bombard your target with psychic white noise with the intent of overloading their senses to cause unconsciousness or, in extreme cases, death. In game terms you use Provoke Will to attack your opponent who defends with Will.
Phantasmagoria (requires Mindstorm): Your ability to affect your opponent's senses now allows you to cause your opponent to experience hallucinations. You use your Will as an attack to overpower your opponent's perceptions which they can defend against with Will. Success means that you cause them to perceive reality as you wish it and get to place a suitable aspect on them as an obstacle. Anyone affected by phantasmagoria can attempt to overcome with Notice, however if this fails they are more convinced that the fantasy is reality.
Etheric Body: With this stunt you may project the essence of your being beyond your physical body. When using this stunt you may are both invisible and immaterial so you may observe the world but not interact with it.
Manifest psi : Your psionic abilities can now take physical form. Mindstorm becomes a physically directed blast of energy, the Illusions of phantasmagoria are visible and audible to all and your etheric body can be seen and heard.
Footnote: Thanks to Porter Williams for his stunt feedback.