Androids are generally humanoid robots, and quite commonly are more or less indistinguishable from regular people, to the naked eye. More advanced models are capable of fighting on a powered level, either physically or by wielding Ki. There have been instances of psionic androids, as well, although they are certainly the exception, not the rule.
High-grade androids designed for combat commonly utilize components to extend their fighting ability. They often incorporate energy cannons, advanced sensors, and flight systems, among other technological devices, within their bodies. As android design will vary widely in accord with the purpose they were designed for, and by whom their designer is, however, it is difficult to give anything beyond the widest generalities about them.