Sashmita,
1. Communicate to the team / business unit that you are hadnling that there's going to be a poll arranged & ask them to vote for anyone in the group who they think is a good buddy, who could lead a person, who has good knowledge about the processes, work methodology & also one who is aware of the group members.
2. Then, send an email that there are cartons / poll boxes kept for people to vote & give a specified time. Collect teh votes, count them & based on the response, decide on the buddies (who have more number of votes). Say, 4/5 buddies can be chosen according to various levels(designations) in the team.
3. Again communicate this to everyone by thanking one & all & inform the names of buddies & probably attach a gift / reward to teh buddies chosen which may act as a motivating factor to them.
4. The real task is whenever a new candidate joins the team, after joining formalities & new associate orientation, introduce the new joiner to the buddy assigned to him. It is with the buddy to take care of this person initially til the settling period.
You need to prepare a handbook for the buddies selected to refer across...
Hope this helps.