Is WoL the only one able to master/handle all the classes at once?

[Vidu]

I mean Thancred went from a rogue to a gunbreaker if that counts..? (and his "rogue" at the start was actually a gladiator)

In addition to that: Y'shtola started out as a conjurer and went on to become some kind of blackmage (or at the very least someone who uses black magic - so shes able to use both black and white magic spells).

Alisae used to be an arcanist aswell, considering that Louisvaix gifted the Twin-Grimoires to her and her brother (whos still an arcanist...) - and now shes a RDM.

Urianger was an arcanist too, but became an astrologian with Shadowbringers.