Can you play with all characters and all variations?

[me is me]

Hi there, I'm not very familiar this game.

Can you play with all different characters in a play through, or do you lock in a subset for the entire game. It also looks like there are different classes. Does choosing one class over another for a character lock you out of the rest?

Can you get all achievements in one play through?

Thanks

[Balkoth]

You're locked to 3 characters per play-through. There are three stories based on your main character. You can't get all achievements in one play-through.

[Jeffer'son Airship]

You pick 3 for a playthrough.

You can change class but it's expensive and later tiers involve farming rare items.

I believe there are a few achievements that are locked to each variation of the main story (there are 3 different end bosses it chooses from based on your main character) and each character.

Its a minimum of 3 playthroughs to get all achievements. The good news is you can always bring one old character from the previous playthrough in as a second or third in new game plus and they'll come in at their old level.

[me is me]

Thanks!

[ryuicy]

your main char defines the main story followed, the story changes slightly when paired with a companion using the same endboss (angela/durand, Kevin/charlotte and Hawkeye/Riesz)
For that play your chars get locked.

Classes can be reset to 1 with a specific classitem found only in later ???-seeds and chests, after that you can choose another path. If you change the basic coruse you have to use ??? seeds to farm the other class items to reach class 3.
(Class 4 items are only given once, don't think you should revoke to class 1 after reaching class 4)

All achievements are not possible in one playthrough, but in 3.

As there are 3 main endbosses fixed on the chars i mentioned above. try using those two for full cutscenes (and learn on which char angela gets a crush :) ) all 6 chars has to be played in those 3 runs to achieve all medals. (Also Anise (NG+) on hard, but she is not really difficult.)

The last one will propably the black rabite which is seriously more difficult as all bosses including Anise, but can be made in NG++

Edit: ah well too late ...

[Jeffer'son Airship]

You can farm ??? seeds that drop the class items later in the game