Send it out, if it's not too late!
Dang it, looks like I missed the party!
The Armadillephant looks fine.
Personally, I wouldn't have given it Int 4, since the original had the same Intelligence as an AD&D elephant I'd have just made it Int 2 like the SRD elephant.
The same proviso applies to the Moat Cat. Both leopards and cheetahs have Int 2-4 in 2E, same as the Moat Cat.
Thus I think making it Int 2 like the 3E big cats makes more sense. Besides, newts aren't noted for being smarter than cats, so it wouldn't feel right to me to make a crossbreed of the two smarter than both.
Looking at its AD&D stats they're very similar to those of a Leopard (AC, Move, claw/claw/bite/rake) or a Cheetah (HD, sprint).
So, I'd take a Leopard and modify its stats a bit - add Aquatic, Amphibious and Water Dependent as previously mentioned, together with a Swim speed and a cut-down version of a Cheetah's Sprint SQ.
Monitor Lizards, Snakes and Crocodiles all have Cha 2, so how about averaging that with the Cheetah/Leopard's Cha 6 to give it a Charisma of 4?
I suppose we could tweak the physical stats a bit if we wanted to. Maybe cut down the Dex by a couple of points (since Giant Frogs and the previously mentioned SRD creatures all have lower Dexterity than the big cats). If we do we should up the natural armour a point to compensate on the presumption its skin may be smooth but is thick and tough, like a killer frog.
So I'm suggesting:
Stats as Leopard, plus:
Magical Beast (Aquatic)
Speed: 40 ft. (8 squares), climb 20 ft., swim 30 ft.
AC: 15 (+3 Dex, +2 natural), touch 13, flat-footed 12
Abilities: Str 16, Dex 17, Con 15, Int 2, Wis 12, Cha 4
Special Qualities: Amphibious, low-light vision, scent, sprint, water dependent
Feats: Alertness, Multiattack