Ok this is just a random idea. Not sure if it can be done or how popular it would be, but I think it would be fun.
What if we could swap out a characters ultimate with the regular ability of another BB. For example, swap Thorn’s Hex blast for Toby’s Arc Mine or Ernest’s Power egg.
The idea is to have an ultra rare drop, the artifact. These would be linked to a certain BB regular ability. If a player was to equip it and activate it, it would replace their ultimate with that ability. Granted some BB abilities on any other BB might seem broken. So we just omit those ones.