Narberal Gamma uses twin dragon lightning which I believe is approximately 7th tier magic. Yuri Alpha uses weather modification magic which is 6+ tier magic. I know they're weaker than the floor guardians, but did the show/Manga/LN go into just how strong they are? I got the impression that each one could have beaten Evileye on their own, but the only reason Entoma didn't was because of vermin bane.
This is what I found elsewhere:
The light novels have the stats, but in order of ranking:
Narbarel Gamma (63) was chosen to accompany Momonga because she was the best combatant of the group and the one that can interact best with humans without being found out.
Lupusregina Beta (59) is just below her and is also allowed to fight autonomously and like Narbarel, also human-like.
Solution Epsilon (57) follows that order as well, being one of the field pleiades though in her case, she's not very good for missions that require excessive contact.
Yuri Alpha (52) is the leader in terms of order, but is significantly weaker than the first half of the Pleiades. However, she is still massively overpowered by NW standards though it still takes her and CZ Delta to keep Evileye on edge. Like the Pleiades weaker than her, she is not a field agent and is generally relegated to the tomb.
Entoma (51) is also comparable, but unlike Yuri, she is freakish up close and is ill-suited for field activity especially since she draws attention to herself.
CZ Delta (46) is the weakest and is actually weaker than some of the strongest new worlders (shown in the latest novel where she needed prep time in order to actually be effective in comparison to the steamroller that is Narbarel). She is generally ill-suited for field activity since her low level makes her a poor choice to work autonomously. However, she is a sniper, so she generally won't be working autonomously on the Nazarick team to begin with.
Aureole Omega (???) is likely the strongest and is generally a function guardian and has yet to appear. However, she is highly likely to be a 100th level NPC due to the insinuation of her role.
Evileye is about level 50 and would have lost to Entoma if she didn't have vermin bane, potions, and assistance.