Aristotle

Unlike Plato , pleasure is not a motion (depature from neutral) nor a repleinishment, implicitely involving a previous state of pain. Pleasure is a state by itself.
Pleasure is concomitant of the normal exercise of the faculties of a living, conscious being (Pleasure is according to nature). Pain results of any impediment in realizing a faculty or expressing a function (Pain is contrary to nature). There is no pleasure or pain if there are no activities (sensory, motor or mental)
For example:

Perceptive pleasure depends on a fully functional perceptual faculty, and an adequate (adapted to the perception) object. The more functional the faculty, the more adequate the object, the greater the pleasure.
Cognitive pleasure is greater than any perceptual pleasure, because it is not submitted to the object-adequacy constraints (thoughts are always maximally adequate).

Pain and Pleasure are not faculties per se (senses and actions), but accompanies (are by-products of) normal faculties. Pain and Pleasure are ultimately linked with actions (motivation to act). They increase or decrease them, but do not select them.
There are different families of pleasure:

Certain pleasure are associated with certain activities, which they facilitate, inhibiting all other activities they are not associated with.
There are 2 kinds of pleasures:

Pleasures of the body: aestetics, conservation and reproduction (eating, drinking, sexual appetite)
Pleasures of the soul: victory, succesful revenge, flattery...

There are different intensities of pleasure (called 'purity'). The more the pleasure depends on 'matter' the less it is pure: intellectual pleasure are the purest, pleasure of tasting is among the less pure.
Pleasure might be in the present, the past (memory) or the future (anticipation). The pleasant memories were pleasant at the time they were experienced, the pleasant anticipations have pleasant consequences.