Robomon are robotic duplicates of pokemon. Their type and moves do not necessarily correspond to the pokemon they are based off of, as such, they can be unpredictable opponents.
Nekoni released three Robomon to battle the people who had shown up investigating the pokemon weakness event. However, she claimed she was 'not into robotics' and was merely 'gathering data for another', if she is telling the truth, the creator of the Robomon is currently unknown.
There were three known Robomon: Proto-Alpha, a charizard, Proto-Beta, a tyriantiar, and Proto-Gamma, a scyther. They were all defeated by the trainers. When defeated, the robomon exploded, perhaps as a security measure. However, there may be more. The fact that these were just prototypes may be worrying.