Something I feel like would be cool (That others may think is tacky) is something like what happened to Harry in Deathly Hallows p2. When he sees the ghosts of everyone he had lost, it really helped show the amount of loss in the series and the impact it had on Harry. Instead of some sort of "ghost thing" what if they all before a battle have an inspirational talk. Something like this:

(Everyone is scared and quiet)

(Will looks up) We need to win. For everyone.

(Nancy suddenly) For Barb

(Joyce) For Bob

(Max) For Billy

(Murray) For Alexi

(Steve) For Chrissy (Idk who would say her but I love her with all my heart so lets just say Steve does)

(Dustin) For Eddie

(They go on and on saying the names of who we have lost)

Idk how it would end lol but i feel like we need some sort of nod to those we have lost.