I don't know whether you check my game page or not but yeah I didn't make tutorial because the time limit is pretty tight, my game has like 16 skills if we total them all its actually 46 (if we included style moves as well) making tutorial about them are likely took a week and again I don't have the time, I even missed one boss.
But of course I aware about that and leave a guide or instructions on the game page about how to distribute the stats, explaining all skills description, game mechanics like special attacks, Crystal Support, and many more, I actually planned to put these too in the game folder in case someone missed it but the upload is already locked.
Anyway thanks for giving my game a try!
As for the tips, if you felt like the first boss movement speed is too fast then try to use Earthquake skill, it will messed the field but it's also slowing the boss down, and look for the Crystal as it can heal your HP/MP or provide buff, they randomly appears on the field but does not vanish until you get them, they also reappear in like around 10 second(you will hear a sparkling SFX whenever they appear), it's sounds cowardly but feel free to stalling when you're in a pinch.
For the second boss... Freezing her with IceDozer work wonder but she sometimes can counter IceDozer so I suggest to build up Stylish Meter to Savage and spam her with Ice Fang(Special Version of IceDozer), the freezing time increases due to a location and weather being either snow or snowstorm but of course your freezing time is also increases so avoid or parry her Ice Lances otherwise you will be the one going down.
Once you beat the 1st and 2nd you are already a skilled so there's no tips for 3rd and the last boss.