New feature idea : Passive team-ups

I just had an idea concerning team-ups, one that could diversify a lot of playstyles.

What if the devs implemented passive team-ups ?

Such team-ups could be active during the entirety of a battle.
Since it would be a little OP in some cases, I was thinking of some drawbacks : they might take the three slots of team-ups/boosts, have a lower drop rate or need to be activated once enough team-ups AP are gathered.

I am not sure if someone already brought this up or not (sorry if that’s the case), so I’d like to hear your opinion on this one.

Passive team-ups… Like supports? … Only in pvp too?

Interesting idea.

That sounds similar to allowing to have a 4th team member in a 3 vs 3 fight. With no way of stunning them.

I’d keep that in store as a 7* exclusive.