Heart Swap
Aqua Ring
Encore
Transform
Metal Sound
Heart Swap should be allowed because it would help Krilowatt against offensive threats. Offensive threats are the only ones that usually use stat-up moves, and swapping away those boosts would be a way in which Krilowatt could counter offensive stat-uppers.
The argument for Aqua Ring being allowed seems to just be "it wouldn't be broken, so allow it." But Aqua Ring encourages walling and therefore goes against the concept. If we allow a move only because it would not be used much, we might as well disallow it.
Encore should be disallowed because Krilowatt should not be a wallbreaker. If Encore were allowed, Krilowatt could switch into any wall using a non-attacking move, use Encore, and force it out. Krilowatt should be countering offensive threats, not defensive ones.
Transform would let Krilowatt beat almost any Pokemon as long as it could force a switch. If Krilowatt used Transform as the opponent switched in a Pokemon to counter Krilowatt, then Krilowatt would almost always have the upper hand, since Krilowatt would have the same stats as the opponent but would (unless the opponent switched in Blissey) have much higher HP. So Transform lets Krilowatt take on too many Pokemon with one set.
Metal Sound encourages Special Wallbreaker sets that are meant to remove Blissey and Tyranitar, since Metal Sound is only very useful against Special Walls. Krilowatt should be a utility counter and not a wallbreaker, so Metal Sound should be disallowed.