This enemy is the Alien variant of St. Pigge the 2nd. She has high health but relatively low damage and range. However, she has 100% chance for a Lv. 3 Shockwave, so she will punish the player for spamming meatshields.
Anything that freezes Aliens and is decently bulky such as Surfer Cat, who can rush in without getting knocked back, can immobilize Elizabeth the LVIth, allowing other units to attack her without trouble (e.g. Valkyrie Cat).
If you are fighting Cli-One or Corrupted Valkyrie in Into the Future's Moon stages and Elizabeth spawns, that is a sign that you have taken too long to beat the stage and that everything is about to go horribly wrong. Either retry the stage, or come back later when you're stronger.
In a late-game scenario she is pretty easy to deal with because of the Wave Shield ability that is on a variety of units and also because she has low damage for a wave attacker. It will be especially hard for her to deal with a stream of Octopus Cats unless heavily magnified. If you were lucky enough to receive oneoftheseubers, then they will be able to deal with her easily. Using units with Wave Immunity is also helpful when fighting her.
56th queen of the Pigpen Kingdom. She turned blue after 7 mushrooms got stuck on her throat, causing her to choke. Moves around without permission using a crown she found around. Can release shockwaves.