As a general rule, "Not advanced" includes:
- Walking
- Running
- Standard Attacks
- Tilts
- Angled Tilts and Smashes
- Smashes
- Dash Attacks
- Special Moves
- Dodging (rolls, midair, and spot-dodge)
- Jumping
- Double-jumping
- Recovery technique
- Wall kicking
- Footstooling
- Grabbing
- Pummeling
- Throwing
- Tether recovery (for those who have it)
Which means Advanced techniques are pretty much the rest (Wavedashing, of Melee fame, or Z/L canceling from Melee and 64, wavelanding, double-jump-canceling, etc).
Basically, if it's in the manual, so to speak, it's not advanced. Most everything else is.
Edit:
Here's an article about it on SmashWiki. Of course, more may be discovered in the future, but for now, that's a pretty good list. As the opening paragraph says, ATs are basically anything derived from a glitch or otherwise unexpected behavior, or (to avoid supreme backlash from some players), requiring a relatively high degree of technical skill.