Server and Local Script - Help?

****If possible, how would you be able to create a Server Side script which would then create and edit the code of a Client Side Script (Local Script) when a new player joins, and if possible could the Local Scripts only be given to certain Players using Tables?

****For example, let's say we want a Server Side script which creates a new Local Script for newly joined Players, that creates a GUI that is a timer (I know there would be no point doing so seeing there is StarterGui). So lets say the Timer was set for a couple of minutes, we wanted it to only start when a new Player joins, just for that Player whilst the other Players timers are different because they have joined earlier.

****Another example would be, say we had a Server Side script once again, yet we wanted it to only give a certain Player the Local Script. For example it could be a script that crashes a Players game, so it would be only given to users in a table called, lets say 'Ban'.

I do not need this in anyway because to me it is not useful, I am just curious and began to wonder to myself as I was browsing through SH and the ROBLOX Wiki Tutorials.