If a botnet is a problem then it show a flaw in the coin. Fix the coin since trying to kill all botnet is a waste of time.
I don't think that statement should even be graced with a response.
Then have fun botnet hunting with Microsoft and Kaspersky.
Ok, I'll bite. How would a coin stop from being mined by a botnet?
By using ASIC technologies thus making the hardware used by botnets obsolete. Maybe there is other methods, I don't know. My point is only that you can't eradicate all botnets. If a coin is destroyed by them then it was flawed.