Scenario 1) Wakka has access to basically every status ailment in the game (except maybe Death and Zombie depending on Standard or Expert Grid), either through his attack skills or through his Overdrive Status Reels. He can also attack with Fire, Ice, Water or Lightning through Element Reels He can take attacks from and deal damage to Sin, Final Aeon and Yu Yevon so i don't think he has much issue even from a power perspective.
Scenario 2) Well he gains Death and Zombie status ailments and Holy (Light), Ultima (Dark) and Flare (non-Elemental) magic attacks. Not to mention can Slow Enemies and use Haste to speed himself up, Heal himself both through White Magic and by Draining energy or mana from enemies.
At the very least, I don't see much being able to take him on in either scenario, he may even clear it outright.