Firstly, its impossible to jot down skills needed by Data Scientist. You could have two Data Scientist with completely different skill sets. However, there are few qualities which are common between all expert Data Scientists.
This list is based on the great article here
Skill #1: Statistics.
Forget the debate between Python Vs R. First thing you need is basic understanding of statistics
Skill #2 :Data Munging – parsing, scraping, and formatting data .
This is where you need to decide on which tool you want to use. If have decided to use Python, this is where NumPy, SciPy, Pandas will come to your rescue.
Visualization is not just plotting beautiful graphs. Its more on your critical thinking, imagination and finding inferences and sometimes letting machines to do the inference.
For Python stack, matplotlib and seaborn will be your tools.
Skill#4: Domain Expertise ( or at least working knowledge )
All of first three skills are required but for you to generate useful analytics, you need to have the domain expertise. You don’t need to be phd in that specific domain. In fact Data Scientist will keep working on different domains at different phases of his career, but he need to have domain knowledge on whatever data he is working on.
Most famous Venn Diagram for Data Science is as below