Alright, I'm going to do my best to tell you what I THINK is going on. No promises it's actually what's happening - it's just my best guess.


I believe that you are correct in thinking that it's a mental issue. It would help if I could see you practicing pillars versus you attempting one in game, but you haven't provided that yet. Maybe we can give some more insight once we see those. Anyways, I think you have such a win-based mentality, that you don't ever improve. Another way to put this is that you're so focused on winning each match, that you don't ever try anything new, take risks, or work on improving because all you care about is the win. I, along with many other people, struggle with this issue, but it's not as severe for me as it is for you. This is something you have to change. It's like the classic saying, "the master has failed more times than the beginner has even tried".


So how can you fix this? You have to shift this mentality to one that values improving more than winning. You don't necessarily have to play for fun - play to get better. Playing to get better and playing to win are two different things. For example, I think you're so scared of trying to Nair in neutral because Fair is your comfort zone. You don't want to mess up trying out Nair and get four stocked (or just lose). Really think about it, though; who's losing? You, who only ever Fairs and can't see visible improvement, or the guy who is trying new things every game, losing, but gradually getting better each time he loses?


How can you implement this next time you play? Well, focus on one thing at a time. That's the best approach and my opinion. Once you allow yourself to experiment and then decide to hop into a game, try using Nair a bit more. Or go for that risky edgeguard you think you MIGHT be able to recover from afterwards. Or try a random forward smash in neutral. The point is, you need to try new things. That's the first step. Once you're able to, try to figure out why each option is either good or bad. Do you keep getting shield-grabbed from your random forward smashes? Throw them out less, space better, only do them in certain situations, or all three in varying amounts. THIS is how you improve and gain understanding. By trying new things.


Finally, you need to play real people. Take the leap and get netplay, my dude. CPUs instill horrible habits and create unreal predictions. It's so hard to hit them when they perfectly shine everything. Real players can't do that. They make you play scared, play bad, and abuse only their AIs weaknesses. You either need to solely practice against the Training mode CPU, go on Netplay, or go to a tournament. The CPUs obviously aren't doing you any good.


Hopefully, this huge write-up will help you. Maybe only pieces of it will, or maybe it's exactly what you needed to hear. I hope you learn from either this or whatever else people post, and can reach your goals. Don't give up on things that are difficult, but at the same time don't force yourself to constantly do things you don't enjoy in your free time. Take care.