how strong are the foretellers? and where would you rank them in order!

[Foxycian]

we never had theard like this i believe so i'll just list who's stronger based on what we've seen
Ira
Aced
invi
Gula
Ava
i hate to admit that As much i love Ava her being the youngest might be why i think she's the weakest as for why i placed Aced above invi well the fact that Aced was pushing invi back the whole fight and knocked her keyblade from her arm and lets not forget the only reason invi pushed him back cause Aced was full of rage he wasn’t thinking straight his fight similar to Aqua and terra, terra being the stronger among the 3 trio but lets his rage consumes him point is despite Aced getting ganged up 3 on 1 he still took down Gula after being weakned yea i can't see invi beating that.

 

[Luxu]

It depends on what category you are ranking them in. As, each seems to specialize in some sort of area.

Gula is the fastest out of the Foretellers.
Aced is physically the strongest out of the Foretellers.
Invi has the most magic mastery out of the Fortellers.
Ira is a bit harder to pinpoint, but it seems to be that he is strongest when using a keyblade. (Reflective of heart strength)
Ava seems to be the Jack of All Trades.

Though, this is just down to my observations.