Short answer: None are good, Cal-S > Spectrier, and Cal-I > Glastrier.
Long answer:
Spectrier would always be outclassed in Ubers by Cal-S. Cal-S boasts higher stats and an expansive movepool than it's normal counterpart, can fit onto Balance / HO / Bulky Offense types of teams, and doesn't require a whole team to be build around it.
The Ubers Viability Ranking state for Spectrier's rank (D Rank)
D Rank
A reminder that these Pokemon are only Ubers by tiering and possess no real metagame niche.
That means, these Pokémon are only Ubers by their tier, and don't have any actual use in the metagame, and other Pokémon perform better than those.
About Spectrier, it lacks any useful option out of it's Ghost STAB, Shadow Ball, and that means that it can't do nothing to Yveltal, one of the most common Pokémon in the tier.
+6 252 SpA Life Orb Spectrier Shadow Ball vs. 252 HP / 252+ SpD Yveltal: 268-316 (58.7 - 69.2%) -- guaranteed 2HKO
A +6 is only a 2HKO, and the Yveltal KO's you in return. Also, tell me, who would be stupid enough to let you setup so quickly?
All in all, Spectrier is quite bad in the Ubers' metagame.
About Glastrier, it's just plainly overshadowed by Cal-I.
Cal-I boasts higher stats and an expansive movepool than it's normal counterpart, can fit onto Balance and Bulky Offense types of teams, and doesn't require a whole team to be build around it.
Glastrier atleast has better options in coverage than Spectrier, but is complete garbage in Ubers out of that. It's also too slow for anything, even Defensive formes of NDM outspeed it can KO a weakened one. Due to the prevalence of normal Zacian in Ubers (far better wallbreaker than Glastrier, and in some ways better than Cal-I also), it just can't mould a place for itself in the tier.
All in all, those are quite bad in the Ubers metagame, and I won't recommend them for sure.
Use Calyrex-Shadow over Spectrier, and Calyrex-Ice or Zacian over Glastrier.
Hope it helped!
