Happy deduces a different solution: the Infinity Clock will stop if the Reborn Oración Seis are completely defeated. This shifts the focus from protection to an all-out offensive.
A significant portion of the episode involves a raw showdown between Gildarts and Byro, showcasing a rare battle that doesn't rely solely on magical firepower ( Crunchyroll ). Context within the Series Fairy Tail Episode 147
As this arc is anime-original (filler), there is no direct equivalent in the original manga's Chapter 147, which instead covers the Nirvana arc ( Fairy Tail Wiki ). Happy deduces a different solution: the Infinity Clock