Elvira herself isn't too powerful, but in the new ELO mode, Rescue has retained its role as a powerful ELO force. As one of the most popular Rescue cards, Elvira is a good card choice to ban if someone wants to weaken the clan. But remember, Elvira is only a player banned card so Elvira will likely be back in ELO next week.
After the UR Powers That Be decided to make almost every staple ELO card banned, Rescue went wild, almost like Girls Gone Wild, except, thankfully for cards like Betty and Pam, they all kept their shirts on. But in ELO, Rescue was everywhere.
The following week, Elvira, Lea, Kerry all were banned BY THE PLAYERS, and Sledj has been put on semi-perma-ban by the UR Powers That Be, partially crippling the clan.
Look at Mona, she's been banned, because she's a huge part of Montana success in ELO. Take her out of the equation and Montana come back down to Earth.
Your comparison only provided further evidence as to why Elvira is banned. First off, Rescue is a powerful clan; capable of both overpowering and over maneuvering an opponent. Rescue has everything: drs, reducers, SOB, SOA... etc they also have one of the best bonuses in the game. This brings us back to the fact that Elvira is simply better then other alternatives in weaker clans. She is better then Otakool, Luis, Tank, Onyx... which are all in weaker clans in ELO mode. So not only does she keep the game imbalanced, but she is blatantly giving Rescue too many options while they already have the advantage of being played in mono (always getting a bonus) and having one of the most powerful bonuses in the game. I am actually pleased that she is now banned making Rescue users at least have to play around one weakness.