In my opinion...
-The grass one looks very similar to Treecko, and I don't really like its design.
-The water one...even after seeing what it looks like I still can't tell what it is. It looks like a polar bear/sea otter/snowman. I would like a polar bear, but a sea otter is more appropriate, especially since we had a penguin last time (which is another thing associated with ice more than water)
-I like the fire one's design the most, and it looks like a pig, which is what I hoped for.
Looking at all of them, though, none of them have an appealing color scheme to me :/ Also they're not really as creative and don't have that same feel the old ones had. (Just look at that water...thing with its annoying orange nose!) Oh, and the protagonists...meh, they're not much different than expected, and they don't really impress me. (except apparently they're older, which I hope is true)