>>39059204well, they mention that is can move very fast to grab prey or something. a real turtle, despite that phrase gaining ire so bear with me, is not horribly slow and in fact has an incredibly fast striking speed. it even almost 1:1 looks the part with the dumb flat-top head. ironically, the only things that look changed from a real goddamn alligator turtle are rounding out the face to make it look more like a steel trap if that is indeed the inspiration, blunting the claws, and adding a crest to the snout. they're also remarkably unruly and bad tempered. we simply don't know, since they didn't mention any sort of pokemon facts outside of eating rocks and being deceptively quick and of a foul disposition.
nessa using it as dynamax isn't the biggest deal. the player dynamaxes stuff like grookey, who we know will have two more evolutions. I don't actually think it'll become an excavator, it was just a valid point. if it is a middle stage or it evolves, I don't think they'd leave the trap theme behind.