Whether or not Giga Impact should be nuked is up for debate, but there is one change to Giga that must be done: lower its accuracy from 100 to 90 percent. Everyone would complain about Hyper Beam being overpowered if its base power were raised back to 150 again, but at least the move still misses from time to time. The fact that Giga never misses is a major concern and part of the reason why Tauros is somewhat overpowered. As for Giga's power, I'll leave that argument alone.