Man, so much Wakka hate up in here. So many people don't realize he's actually better than Tidus if you get a good weapon for him.
Tidus has better HP and Def, but Wakka can do full damage from the back row. Having 50% damage mitigation from being in the back row basically doubles Wakka's effective HP (vs physical attacks), which makes him way better at surviving than Tidus.
They have equal Atk, but Tidus has better weapon selection. If you got Wakka's 5* though, you can throw Tidus' weapon advantage out the window (pun intended
). Hell, I've been using Wakka with just a 3* Shuriken I pulled when I first started and he's been doing decent with it.
Lastly Tidus' normal Soul Break has better utitility for bosses than Wakka's normal Soul Break (unless the boss is weak to Water), but Wakka's Soul Break from his 5* is basically a Mental Break + Armor Break in one, saving you two ability slots while not even taking up one!
Seriously, Wakka's a better Support character than Tidus to begin with, and if you got his 5* that makes him
miles better.