yeah, but i can normally judge just right for when to use the bat.... i don't know! it will be more clear of what you would need to work on when you start playing again. basically the only thing i can contribute is that every attack can and should be used at least once per match, some weighing more heavily than others (fair should be used many more times than dair, or psi magnet (lolz) should be used more than pkfire... waitwut?!?!). you are the one who must determine when each attack is most useful and in which way to have it used during a game you are playing against others. people can truly only give suggestions as to what is best, but eventually you will define how you play.
A few suggestions from myself:
#1: learn to EFFECTIVELY spam PSI magnet.
#2: get a feel for all of the attacks again (proper spacing, when an attack will most likely kill a person, which way to make pkt go to have pkt2 go the exact trajectory you want, ATs, etc.)
#3: play other ness mains (irl or wifi) and pay close attention to how they play and where they beat you out, then try incorporating what they do. mastering your opponent is how you master yourself.
#4: AFTER ALL THE OTHERS, (maybe joking about psimag, but you can if you want to) try and change at least one thing, if possible, about how you play, but ensure that it will do more help than harm before going all out with it. being unique will ensure that you keep an extra mindgame ahead of your opponent.
EDIT: my post # is the same as the number of degrees from adding up all the angles in a quadrilateral OR from a full rotation
and by effective spamming of psimagnet, there is really no way for me to explain exactly how, because i can't explain... there are so many different aspects involved in it that it would just confuse everyone and not help at all... maybe i should start a thread about that... or ask Ref/EB360 to add some info to their psimagnet sections... althouggh it still wouldnt help. basically you have to get a feel for absolutely everything involving psi magnet, even using the wind at the absolute right time to push your opponent just far back enough to not get hit, and try to see where you can slip it in... speaking of PSI magnet wind, NEVER use it against marth... or ganon.... maybe not snake... or DK.... or a projectile (notice wind; not talking of not absorbing attacks that you can, because you should).... yeah, just get a feel for it and the ranges of other characters' attacks.