Can anyone here teach me the advanced SSBB techniques? I've got down the basics, but I've noticed that as of late, I'm not improving at all. Considering I play 3+ hours a day, that's fairly distressing :(
I'm not entirely sure you understand the question you're asking.
Whilst how you get better is highly dependent on who you main, learning 'the ATs' is not what you need to be doing. This is true even if your character is very AT dependent. You will want to practice ATs as a part of everything else, but trying to get better by using them and only them is just going to make you worse.
Training to achieve complete technical mastery of smash, and your character, will make you a better player.
I assume this is what you meant by 'advanced SSBB techniques.' However, it only does so by giving you more tools. Playing real people is (obviously more) important for specific match-up experience, and general playing experience (knowing how to apply these tools).
When you practice alone you're trying to improve technical proficiency with your character - that's it. You're not going to get instantly better by improving your technical proficiency*, but as you begin to play matches and apply what you have been practicing, you will improve rapidly.
If you are regularly playing players at-or-above your skill level, and the practicing isn't helping, then either you're not practicing right, or you're not playing intelligently. How you practice is highly dependent on you, and highly dependent on your character.
This thread applies to Marth, but you might find it helpful.
*this is more with ATs, attack strings, chain grabs, and advanced movement. Powershielding, teching, and training like that will of course make you instantly better (provided you do it right / consistently).
