Pollen is not transferred from one flower to another (either on the same plant or between plants), but instead the process of pollination occurs within each individual flower. Pollination takes place within a single flower, usually before it even opens. Other flowers or plants are not needed.
Self-pollinating flowers are called “perfect flowers” because they contain the stamens that produce pollen and the pistil that receives the pollen. Isolation distance used to prevent cross-pollination is unnecessary for such plants, unless insects are known to invade the flowers before pollination is complete.