A brief description of Amelia's currently available moveset. I'll be referring to buttons with PS4 pad notation.
Square, square, square... - A combo that starts with a fast kick, goes into a backhand punch then attacks with a remote polearm spin. Quite linear, and most parts can be jump and dash cancelled. The final polearm attack leaves the enemy quite far away, so dash cancel to get closer or follow up with a few gun shots. You can also cancel back and forth between square moves and triangle moves to switch up your combos a bit.
Triangle, triangle, triangle... - A combo that starts with a slow, wide polearm swing, then goes into a long spinning combo that ends with the enemy in the air, and slams them down with a final remote polearm attack. Some parts in the middle can't be jump cancelled, but can be dash cancelled. This attack has a much wider range than the square combo but each move takes longer to come out. The entire combo takes several seconds to complete, so if there's an Arbalest or Probe with its sights on you it can be tricky to reach the end of this combo without having to dodge first.
Midair square, square, square... - A juggling combo with the polearm. A few faster attacks at the start are followed up with a lengthy spinning move, which is finished with a descending spin attack that drags the enemy to the ground with you. Each attack can be cancelled into a midair triangle, but note that the long spin move cannot be cancelled except into a jump or dodge.
Midair triangle - A simple diving move that descends straight down while attacking with the polearm. It has a thin range while descending, but a large splash range on the ground. The splash damage also pops enemies up a bit off the ground.
Triangle while dashing/running - Amelia surfs on the polearm for an advancing attack. Hits three times and can be cancelled into the second hit of either the square of triangle combo. Can also be jump cancelled and dash cancelled. A high-value move with lots of applications.
Jump, then triangle quickly - Similar to a move with the same execution in Bayonetta, bring an enemy up with you into the air with an upward polearm slice. The enemy will be suspended in front of you and you can follow up with a jumping square combo, or...
Jump, then triangle, triangle quickly - After performing a launcher, quickly follow up by dragging the enemy back to earth with the same descending spin move as at the end of the midair square combo. Good damage and gets you back to the ground where you can switch targets if needed.
Amelia's Transformed Moves
Holding L2 will alter Amelia's appearance and change up her moveset slightly. You can cancel from many regular moves into transformed moves, so experiment.
L2 + square, square... - Amelia's ranged option. While transformed, light attacks are changed into hitscanning gunshots. Unlike gunshots in other action games, these can put hitstun on an enemy from afar so you can interrupt a Probe or Arbalest attack with them. When locked on, the shots will go directly into the enemy but if you're unlocked, they can be aimed manually with the reticule that appears while transformed. Gunshots can also be fired in midair, but the rate of fire is far lower than when on the ground.
L2 + triangle - Performs the same launching move as jump and triangle quickly when not transformed.
Midair L2 + triangle - Performs the same divekick as when not transformed.