Consider a situation in which you are moving two point charges such that the potential energy between them decreases. (NOTE: ignore gravity). This means that you are moving the charges:
a) Closer to each other
b) Farther apart
c) Either A or B

Option A

Explanation:

The potential energy decreases in the case when the charges are opposite and they attract each other.

In this case there is no external energy required in order to put the charges together.

This is so because the charges are opposite and they will attract each other. Yes, the only condition should be that the charges should be alike.

Example: a negative charge and a positive charge.