Ecto Baa Baa is the Floating variant of Baa Baa. It's two times more powerful in terms of health and damage, effectively becoming a Floating Hippoe, but it is still hardly a threat.
Strategy
Since it is only twice as strong as the regular Baa Baa, almost anything can kill it with ease.
The blue flames next to it are hitodama, which traditionally surround Japanese ghosts and those they possess.
Due to the near-identical katakana spellings, the Ecto Gang's Japanese name, Ghost Masters (ゴーストマスターズ Gōsutomasutāzu), may be a reference to the movie Ghostbusters (ゴーストバスターズ Gōsutobasutāzu).