Ok, basically what He says to us, defines our moral constuct.
As such disobeying Him would constitute immoral conduct, and following Him, moral conduct.
It depends who you refer to, as if you are talking about the Father, then He is both incapable of being tempted, or doing evil.
The Son (Christ) was actually capable of being tempted, but regardless (there is dispute as to whether He was able to sin or not) He didn't sin. Temptation =/= sin itself.
So in either case, neither of them do sin or do evil. In that way they are morally perfect.