What size tank?
I'm assuming the paradise is macropodus opercularis.
Female bettas with the paradise are a definite no-no. That'll end in disaster - probably for the bettas.
As for keeping one with croakers, this depends somewhat on the circumstances. In the case of paradise fish, it isn't always looking similar that causes problems. Paradise fish can just generaly be aggressive. Females are less so though. In a big, planted tank, croakers and a couple of female paradise fish (two females so they occupy each other instead of going after the croakers - if you can manage 3 females, that's even better so one doesn't get stressed by the other - avoid males as they would just add to the number of issues you'll need to deal with) should be able to co-exist relatively peacefuly. Unlike many other gouramies, these two species don't actualy tend to stick to the upper layers and they don't usualy restrict themselves to setting up a territory at the top either so this isn't a major issue. However, croakers are generaly considered peaceful, even timid/shy fish while paradise fish are better suited to a boisterous to semi-aggressive community. Mixing the two would be risky. It isn't impossible, but you need to provide the right mix of tankmates and in the right environment.
