Unfortunately, not a single one of them could withstand the Thunder Tribulation.
"No wonder we rarely see any Class III spirit beasts... unless they were innately of Class III, it's exceedingly difficult for lower-tier spirit beasts to overthrow their own status and achieve Class III,"
After a multitude of experiments, Wang Ba finally arrived at this conclusion.
Aside from this, his greatest gain was acquiring a sufficiently clear understanding and comprehension of the Golden Core Thunder Tribulation. He even faintly felt that if he were to go through the Tribulation himself, he might actually be able to survive a few rounds...
Of course, he also felt that perhaps it was because most of these spirit beasts were forced to mature by him, their bodies lacking enough training and they hadn't truly reached their intended state.