unionall.ssb is a file, containing the game's coroutines. Those coroutines are used to show a cutscenes, return controls to the player after the dialogue with NPC, make a Cutscene -> Overworld transition etc.
You can call those coroutines with CallCommon, JumpCommon, ExecuteCommon and supervision_ExecuteCommon opcodes.
Coroutines
coro END_TALK
coro WAIT_START_FUNC
coro NORMAL_WAIT_END_TALK
coro LIVES_REPLY_NORMAL
coro LIVES_REPLY
coro OBJECT_REPLY_NORMAL
coro LIVES_ACTING_NORMAL
coro ENTER_WAIT_FUNC
coro TALK_UNIT
coro TALK_ADVENTURE
coro TALK_ATTENDANT
coro TALK_PARTNER_MESSAGE
coro LIVES_MOVE_NORMAL
coro LIVES_MOVE_CHANGE=
coro LIVES_MOVE_PARTY
coro OBJECT_MOVE_NORMAL
coro OBJECT_MOVE_CHANGE
coro PERFORMER_MOVE_NORMAL
coro PERFORMER_MOVE_CHANGE
coro MOVE_INIT
coro MOVE_PAUSE
coro MOVE_STAY
coro MOVE_SLEEP
coro MOVE_RANDOM
coro MOVE_TYPE1
coro MOVE_TYPE2
coro WAKEUP_FUNC
coro WAKEUP_FUNC_SERIES
coro LOOK_AROUND_FUNC
coro LOOK_AROUND_FUNC_SERIES
coro LOOK_AROUND_DOWN_FUNC
coro LOOK_AROUND_DOWN_FUNC_SERIES
coro LOOK_AROUND_RIGHT_FUNC
coro LOOK_AROUND_RIGHT_FUNC_SERIES
coro LOOK_AROUND_LEFT_FUNC
coro LOOK_AROUND_LEFT_FUNC_SERIES
coro JUMP_HAPPY_FUNC
coro JUMP_HAPPY_FUNC_SERIES
coro JUMP_SURPRISE_FUNC
coro JUMP_SURPRISE_FUNC_SERIES
coro JUMP_ANGRY_FUNC
coro JUMP_ANGRY_FUNC_SERIES
coro LOOK_AROUND_FAST_FUNC
coro LOOK_AROUND_FAST_SERIES
coro HEAD_SHAKE_FUNC
coro HEAD_SHAKE_FUNC_SERIES
coro EXPLANATION_FUNC
coro EXPLANATION_FUNC_SERIES
coro INIT_SLEEP_FUNC
coro INIT_SLEEP_FUNC_SERIES
coro INIT_BASE_FUNC
coro INIT_BASE_FUNC_SERIES
coro HANYOU_SAVE_FUNC
coro NORMAL_MESSAGE
coro NORMAL_EVENT
coro NORMAL_CAMERA
coro EVENT_FORMATION
coro EVENT_EVOLUTION
coro EFFECT_MOVE_DIVE
coro EFFECT_MOVE_WAVE
coro EVENT_DIVIDE
coro EVENT_DIVIDE_NEXT
coro EVENT_DIVIDE_INIT_FUNC
coro EVENT_DIVIDE_NEXT_DAY_FUNC
coro EVENT_DIVIDE_NEXT_DAY2_FUNC
coro EVENT_DIVIDE_FIRST
coro EVENT_DIVIDE_SECOND
coro EVENT_DIVIDE_AFTER
coro EVENT_DIVIDE_RESUME
coro EVENT_DIVIDE_SPECIAL_EPISODE
coro DEBUG_SCRIPT
coro DEBUG_SCENE
coro DEMO_CANCEL
coro DEBUG_FLAG_SETTING_BIPPA
coro DEBUG_FLAG_SETTING_PUPURIN
coro DEBUG_FLAG_SETTING_FUTURE
coro DEBUG_FLAG_SETTING_CHARMS
coro DEBUG_FLAG_SETTING_KIMAWARI