As I read it, 1 is not a sentence, but a phrase (perhaps a clause) as in "Bajaj; serving as Backbone support to run the first ever online competition by Microsoft; also coordinates several other support services".
3 is the correct sentence, though I would also add the word "as" after "serving". Without the word "as" the sentence implies that Bajaj is a servant and Backbone is a master.
However I would rewrite the whole sentence to this: "Bajaj is providing support services for Backbone for Microsoft's first-ever online competition.
Lasty, is Backbone: Backbone.js? Unless the audience knows what this is, I might clarify this as well. Is the support for programming or for others using it? Or is it hardware support to help it function? Or is it some other type of support?