This is a really really fun game. The references to everyone are awesome and honestly I feel like even the placeholder sprites are good enough to be representative of the member. I would really like it if you could right click on a unit before buying them to see what their details are as well. Nerissa turned out to be broken because stun is just that good. Keeping enemies within range of other units makes it so even if I don't level her up she's still an amazing team member.
I also ran into some bugs though. I also ran into the bug Slimjim described where if you sell and buy a unit in the same level sometimes it gets put on the same spot as another unit, making both unusable. I also ran into a crash, and I'll put the error message below. I also noticed that sometimes the enemy counter at the top would go past the maximum, showing something like 20/11 enemies defeated. I think this is where your bug is, since in both the Anya bug he found and my Suisei bug, they were targeting enemies that didn't exist.
Another QoL thing is if you show a unit's details and don't get rid of the text box, it stays on screen during the unit placement and round and you can't get rid of it.
Very fun game though. I can imagine myself spending a lot of time playing this.
############################################################################################
ERROR in
action number 1
of Alarm Event for alarm 0
for object obj_SuiseiUltimate:
Unable to find instance for object index -4
at gml_Object_obj_SuiseiUltimate_Alarm_0
############################################################################################
gml_Object_obj_SuiseiUltimate_Alarm_0 (line -1)