The shape depends on the force felt by the participants. When the distance between particles is bigger than their radii, you have only minor changes. But, at closer distances, in the order of their radii, you can have strong changes of mass and "bond energy" . It depends on the specific situation of interactions.

In all scattering experiments ever conducted, electron have always behaved as if they were point-like, with no unbreachable limit ever encountered at any distance from their centers, contrary to protons and neutrons, however close two electrons being made to collide frontally, for example, came to each other's centers.