More like:
Ciel-> Hardy-> Terra-> Amaria-> Titania-> Adrienn-> Saphira
Ciel's TM weak to Hardy (Unless it's Roost, which is not the case.)
Hardy's TM weak to Terra (Unless it's Stealth Rock)
Terra's TM weak to Amaria
On the other Gym leaders that would not be the case.
We have plenty of fire pokes for Titania, poison(a lot)/steel for Adrienn and currently we can catch ice ones(Mamoswine included) for Saphira