For the green:
The energy types in 3.5 and 5e have been Acid, Cold, Electricity/Lightning, Fire, Sonic/Thunder. Explicitly as energy types in 3.5 and as the damage types that are stopped byPortecton from Energy Spell in 5e. We get four of those for the chromatic dragons, but then Sonic/Thunder is left out... and the Green gets its classic something like chlorine gas (is that corrosive or poison? depends on edition). The loud roar equivalent in the forest/jungle feels like a thing (and maybe some Savannah too).
For the blue:
I like the lightning breath, and can picture the blue dragon soaring in the skies, with dark blue maybe blending in some for those looking up during an approaching storm, or light blue in general. It feels like I want them living on high places overlooking where the storms would be (so a tepui, or loan mountain, or mesa). Burrowing in the ground in a desert just doesn't fit as well for me.