One more time, so hopefully people stop talking about notations!
The buttons are map-able, which means that Triangle is not the same move for every player. The game refers to the buttons as "Attack 1," "Attack 2" and "Attack 3." Which makes 1, 2, and 3 the correct terms.
I'm somewhat skeptical that some of these combos are inescapable but I'll try them out later. Side Square into Up Square definitely didn't combo in the beta, unless it only works in a specific circumstance (like if you don't start the combo from Air Side Circle, for example).
It's also worth noting that the game's AP display is somewhat unreliable - it will report certain things as being combos even though they aren't. For example, just keep doing Air Side Circle, Square over and over again. The AP counter keeps going up, but it's not a true combo.
Every single combo I listed is a true combo. I'm not testing with the AP gauge; I'm using the "Attack Data" display, which MAJ said was 100% accurate.
Side 1 into Up 1 does combo, but it is not reliable. It requires specific timing. Other than that, the only requirement is that the Side 1 hits an opponent that is close to the ground (they can be in the air...as long as they aren't very high up). Like I said, those were just quick combos for examples.
I've found some more ways to combo into Level 1 and Level 2 supers. Most aren't necessarily practical, but some are.
Level 1: --- D1 (with back to opponent). This juggles right into the super. --- Neutral 3 (the fireball) will juggle into a super. The easiest way to combo this is (3~1, Super). You just have to time it so the dash meets with the person right before they recover. Not too difficult. --- U3 will also juggle into a super, but you have to hit an opponent with it at point-blank range. This is not practical. --- j.S1 can juggle into a super, but it must be done as close to the ground as possible (as well as point blank range). Totally not practical. --- j.D1 can link to a super, but the j.D1 must hit while you are close to the ground. Not practical. --- Neutral 2 can combo into super 1, but it is difficult to set-up. The first hit of Neutral 2 has the same stun as Neutral 1, but the second hit has hardly any stun. If you get the spacing right, then you can cause the second hit to whiff, leaving the opponent in a long stun. After that, you just have to get a tight link into Super 1.
Level 2: --- Neutral 3 (the fireball) will juggle into a Chicken attack. The super must be activated before the fireball hits the opponent. This is easily done with (3~1, Super) as long as you aren't standing directly beside the opponent. --- U3 will also juggle into a Chicken attack, but you have to be at point-blank range. The super must be activated before the fireball hits. Not practical. --- D3 or j.D3. The explosion can juggle into the jumping Chicken attack. This is not practical, but I do have an example combo that does work: j.D3, j.D1, D1, S3, Super, (explosion launch), j.Chicken ----- Must be done against a wall.