BlazBlue: Calamity Trigger

Perform an Astral Finish with every character:
Some people had some problems with this achievement unlocking, and some problems actually getting a character's Astral Heat to activate. Here are the conditions you need to make sure you get it:

Step 1: Unlock every Astral Heat.
To unlock a character's Astral Heat you will need to complete Arcade Mode with that character. The exceptions being v-13-, Rachel-Alucard, and Ragna-The-Bloodedge; all 3 of those characters have their Astral Heat available from the start.

When you complete arcade Mode, after the credits and game over screen you'll end up back in the menu and the game will alert you that the Astral Heat has been unlocked for that character.

If you're not sure who you've completed Arcade mode with then you can check the gallery and look for each character's ending video, if you haven't completed Arcade mode the video will still be locked in the gallery.

To get this step done faster you can set the difficulty to Beginner, the rounds to 1 and the time limit to 30 seconds. You can also use as many continues as you'd like.

Step 2: Setup the Conditions
For an Astral Heat to be performed the following conditions must be met:
-it must be the final round (ie: if it's 2 out of 3, it must be the 3rd round)
-your opponent must have less than 20% health (a good way to tell is their special meter will automatically climb when their health is below 20%)
-your special meter must be at 100%

For the Astral Heat to count toward this achievement the following ADDITIONAL Conditions must be met:
-it must be done in Versus, Arcade, Score Attack or Online Mode
-the match must have at least 3 rounds
-the player earning the achievement must be Player 1
-the Astral Heat must connect ending the match in an "Astral Finish"

Step 3: Performing each Astral Finish
In order for the Astral Heat to count as an Astral Finish it must connect with the opponent and damage them enough to end the match. Here are the conditions to ensure that each character's Astral Heat connects:
(I recommend making sure you've got the default button mapping)

v-13-: Stand close to your opponent, push SP4 (Down on right stick)
Iron-Tager: Stand close to your opponent, push SP4 (Down on right stick)
Lichi-Fay-Ling: Stand just outside of attack range. [ush D (A-button) to plant your pole, push SP4 (Down on right stick) to jump on top of your pole
Taokaka: Stand very far away from your opponent, push SP4 (Down on right stick)
Noel-Vermillion: Stand close to your opponent, push SP4 (Down on right stick)
Ragna-The-Bloodedge: Stand close to your opponent, push SP4 (Down on right stick)
Jin-Kisaragi: Stand close to your opponent, push SP4 (Down on right stick)
Rachel-Alucard: Stand close to your opponent, push SP4 (Down on right stick)
Carl-Clover: Jump behind Nirvana, hold Drive (A-button) and walk Nirvana so that she is standing close to your opponent, release Drive and distance yourself, push SP4 (Down on right stick)
Arakune: Jump up from just outside of attack distance, on your way back down before hitting the ground push SP4 (Down on right stick).
Bang Shishigami: Stand just outside of attack distance, jump straight up, at the very peak of your jump push SP4 (Down on right stick). Immediately after pushing SP4 have your opponent jump straight up.
Haku-man: Stand close to your opponent, push SP4 (Down on right stick) immediately after pushing SP4 have your opponent spam their Weak Attack (X-button).

Tips for getting it done quickly:
I recommend going into Game Options and restoring the defaults, then change Versus time limit to "Infinite".
Start Versus Mode and turn on a second controller. Have the second controller be Player 2, and pick Iron Tager every time (he has the largest hit box so he's hard to miss).

You play as Player 1 and pick the character you'd like to perform the Astral Heat with. Have the second controller win the first round, then you win round 2. On the 3rd round beat up on your opponent with simple strong attacks until their health bar is low (I usually go until it's below the barrier bar).

If you're not at 100% special meter yet have the second controller beat up on you with simple weak attacks until your special meter is at 100% or until your health is below 20% (which ever comes first).

Perform your astral heat as described in step 3 above. If you miss (which might happen with a few of the more tricky ones) just make sure your health is below 20% and wait for your special meter to refill.

If you performed the move correctly you'll see the word "Heat" on the screen, if it's counted as an Astral Finish you'll see the giant "Astral Finish" graphic on the screen once it's over.

You'll get dumped back to the character select screen... rinse and repeat.

AFAIK there is no way to keep track of which ones you've performed so you'll have to keep track of it yourself.

Achievement is: Discouraging Finish! -- Use an Astral Finish with every character.

First, you must either complete Arcade or Story mode with every character EXCEPT Ragna, Rachel, and v-13 (as they have their Astral Heats unlocked at the start). Arcade mode is a lot faster than Story.

Then all you need to do is set the number of rounds for a game of versus to one, bind a button to SP4, go into versus with two controllers plugged in, pick each character, get your opponent under 20% health and hit SP4 once you have 100% meter. Either you or someone else needs to hold back block a bit on the other player (since 100% damage will not yield 100% meter for any character), or get your character below 20% first (since then you start automatically generating meter slowly).

Then just rinse, wash, repeat with the other 11 characters in the game. A couple have special conditions (like Litchi must be standing on her pole, Hakumen must land it as a counter) but you can find this information in the command list in-game.