Low ability scores and a bad breath weapon with weak SLAs. At least they have a reasonably easy-to-trigger fast healing clause (ask your DM if a Continual Flame counts: RAW it probably should). Even so, I don't think this one deserves -0. Any who disagree should say so.
Breath weapon is an icy version of the dust mephit's. Slightly weaker in my opinion, though not enough to matter much. SLAs are pretty bad, and so is the fast healing clause (though the Chill Metal SLA can explicitly create ice from water, so that helps). AC is highest amongst all mephits, if that matters. Another +0 edging close to -0 LA.
What is it with fire-subtyped creatures and lower ability scores? It's the same with fire elementals.
Breath weapon is the now-familiar penalizing version, this time adjusted to deal fire damage. It's okay, I guess. SLAs are Pyrotechnics and a custom effect that allows the mephit to turn into a magma pool, both of which are pretty badly-written. Depending on how your DM reads it, it's either an incredible defense or inescapable trap. Finally, the fast healing clause, which is literally the fire mephit's, but better.
Another for the +0 LA pile, it seems.
These guys have a swim speed in addition to usual mephit movement modes, as well as above-average strength and constitution. Breath weapon is an acidic penalizer, SLAs are Acid Arrow 1/hour and Stinking Cloud 1/day (which is decent enough). Fast Healing works only in wet or muddy environments: in a pinch a Create Water spell should do.