Alright, here is what you do. In order to get Meta Coolers Galaxy you need to beat Cooler's galaxy, and in order to unlock Cooler you need to beat Freeza's Galaxy.
Once you beat Freeza's Galaxy go to Cooler's Galaxy and there should be one there that gives you "Seal Near Death Start III" which will negate the effect "Start at near death" in the higher up characters such as Broly and all the best characters.
Indeed the whole "Health Auto-Gain" you get from Meta Cooler's Galaxy is indeed handy the best thing to do is to get the Seal Near Death items from Goku's Galaxy, Cell's Galaxy and, again, Cooler's Galaxy.
In a world of Chaos I am the Light, and in the world of Light i am Chaos - Made by me, copywrited to me.