4th house will remain watery bhava , as moon and venus both karaka of this bhava are watery planets. this house represent mother and emotions , so this will be watery bhava irrespective of sign or planet. but flavour of prediction would change for different signs and planets.
rasi is the way how things are done but bhava tells what things are done.4th bhava is the bhava of mother ,if airy sign or planet is placed in this bhava ,then mother would show affection in analytical way not on a emotional way.
same would be true if malefic planets aspect this bhava or placed in it, as they will dry up the water(emotional) part of this bhava. but watery planet in this bhava would make more affections and emotions.

planets in pushkara navamsh gives good result irrespective of being debilitated, or retrograde.
they will give good results pertaining to the house they are placed in, irrespective of them being in dusthana house. but they must not be severely afflicted, because if afflicted they will give results in a malefic way but for good of you so that you become better.

you can see video of vp goel sir on pushkara navamsh.he is a great teacher of astrology.

mars have signification of being bold and not afraid of anything, just increase his power in your chart if you want to be bold. you can do by planting neem tree and eating its leaves daily. And when anyone needs your help,give them your physical help and never say no. always smile like hanumanji while doing work ,if any challenge comes then face it and dont be frustrated or start using abusive words because of frustration.

*the question is why mars in 3rd house is brave?*
3rd house is also the house of perspective, your thoughts. as mars is army general he takes over challenge and finish it without getting frustrated and never say why i’m stuck here to do this. that’s why mars is karaka of 3rd house.
so just change your thought and perception when you see something.