Have actually been asked this same question before but there’s no harm in thinking of some more…
My favourite dinosaur as a kid was Parasaurolophus (not exactly a traditional choice, I know, but to each his own), but I’m not immediately sure what you could do with her. Parasaurolophus’ schtick is her long hollow crest, the function of which is a recurring topic of debate among palaeontologists, though it seems likely that it had something to do with communication, since the cavities in the horn are connected to the dinosaur’s nasal passages and could have produced a sonorous booming call at will. Sonic powers aren’t exactly unique in Pokémon, though. Maybe instead you could run with one of the more famous of the older, discredited hypotheses – that the crest was a snorkel – and make it amphibious or aquatic, but not actually a Water-type? Sort of a Grass/Ground (or maybe just Ground with Water Absorb or something) swampy kind of creature, that submerges itself for hours at a time to hide from predators.
I leave you with a quote from the Wikipedia page on Parasaurolophus:
“One unusual suggestion, made by creationist Duane Gish, is that the crest housed chemical glands that allowed it to throw jets of chemical "fire” at enemies, similar to the modern-day bombardier beetle,“ so in fairness we can probably give the damn thing whatever powers we like.
See also this glorious image from one of Gish’s books directed at a younger audience. I especially love the way the other dinosaur flails helplessly.
Pokémaniacal 