Here's the unexpected character options I would like to see.
GARLIC JUNIOR
Instead of him being a rival for Kami, Garlic Jr. was a rival to Beerus to be the next God of Destruction, but Garlic wasn't chosen. Beerus once mentioned that the gods have a sealing method. This method is the Dead Zone. So when Zeno became frustrated with Garlic Jr., Beerus used the Dead Zone to seal Garlic Jr. Away. Many yrs later, he manages to grow powerful enough and somehow Garlic Jr. escape the Dead Zone. Then Garlic Jr. uses the Dead Zone & seals away Goku and company in a realm where ki is capped/mostly blocked (like a plot point in FighterZ). This gives everyone time to fight Garlic Jr.'s evil minions until they can break out the Dead Zone. It also gives possibility for unlikely team-ups like Goku/Piccolo, Vegeta/Yamcha, Krillin/Goku, Gohan/Vegeta, Piccolo/Tenshinhan, 17/Piccolo, 18/Krillin, 17/Krillin, Roshi/Goku/Krillin/Yamcha (Kame School), ect.
In this version, it's is impossible to die in the Dead Zone (hence the name). Then after defeating and sealing the minions away, they all team-up to finish off Garlic Jr., despite everyone being unable to use their full power.
A great ending would be Beerus breaks into the Dead Zone & Beerus goes all out against Garlic Jr. in his GoD transformed state (because GoD Toppo reminds me of buff Garlic Jr. So imagine if his buff form was his Destroyer transformation.)
We would get to see Beerus' full power & make Goku want a rematch with him again after Beerus wins.
TARBLE
(I really like Tarble, plus he is the last Saiyan with a tail, so that makes him really cool! Also his wife Gure is cute, so bring her back.)
Tarble comes to Earth to warn Vegeta and the others of a threat that is coming and it destroyed the planet Tarble lived on. I'd have a scene where Tarble goes Super Saiyan & creates an artificial moon, then we get a Golden Oozaru vs whatever the enemy is (hint at SS4 to tease fans but don't show it). After the big battle, Goku and the others are out of energy and are about to be defeated. As a last resort, Goku, Vegeta, Gohan, Goten, Trunks, & Tarble perform the SSG ritual. This re-energizes Goku. The artificual moon is still present & this causes Goku's SSG firm to look slightly different & has red around his eyes (another tease of SS4). Goku defeats the bad guy.
Also, I would have Launch return for this movie for some comedic interactions. Awkwardness between her & Tenshinhan, Lunch teasing Krillin about being a cop & she has a connection on the inside with him, Lunch & 18 finding each other similar & getting along quickly, her making fun of Vegeta & he tries to ignore her, ect.