Marking Progress:
I know I'm skipping ahead, but I think this should have been talked about first. Upon entering an area the DexNav will show a representation background for the area. As you encounter Pokemon in the area it'll have these Pokemon show up. If you merely encountered the Pokemon but didn't catch it it'll only appear as a silhouette, but if you did catch it it'll appear filled in. Once you caught all Pokemon found in the area, you'll get a mark indicating you did (similar to BW2's
Habitat List).
Opinion: A nice feature to have, I liked filling out the Habitat List in BW2 and can't wait to fill out the DexNav in ORAS! Though the example pic confused me a bit. According to this Route 103 is completed once you catch a Zigzagonn, Poochyena, & Wingull in the grass and a Wingull while surfing. But according to Bulbapedia you can still encounter Tentacool and Pelipper while surfing AND a Tentacool, Magikarp, Wailmer, and Sharpedo while fishing. So did they decrease the amount of Pokemon you can meet in each area?
Hidden Pokemon:
Sometimes you'll see a part of a Pokemon sticking out of the grass or splashing out of the water. The DexNav will display a magnifying class icon which, when pressed, will tell you some info about the hidden Pokemon.
At first it'll tell you very little, it looks like only the level, but as you encounter more and more specimen of that species you'll increase our
Search Level and more info will be revealed to you like its First Move, Ability, and Potential. Eventually you'll be able to find Pokemon with their Hidden Ability and even rare moves this way!
But in order to battle this Pokemon you'll need sneak up onto it. If you walk up to it it'll notice you and run away. In the game I'm sure they'll tell you what the "sneak" button is.
Opinion: Awesome! The DexNav essentially does what we wanted the Pokedex to always do: tell us about the Pokemon we're about to capture! I'm going to guess those rare moves will always be in its first move slot, otherwise it'll be useless to tell us that otherwise. Also I'm wondering what they mean by "Potential"? Also it's kind of disappointing they don't show us the Pokemon's Nature, but I guess they'll only want to tell us so much and I'm guessing once you're at that high of power every encounter with that Pokemon would result with a similar Pokemon. Also I wonder what they mean by "rare move"? Is it a move this Pokemon can't normally learn? An Egg move? A move it normally learns at a later level? Finally, I'm hoping that maybe this sneaking feature could be used to get around trainers...
Searching For A Pokemon:
Ever wanted to just look for one Pokemon? Well now you can with DexNav! Just tap the Pokemon you want to search for and if there's on in the area it'll pop out of the grass/water. Sneak up onto it and the rest is up to the battle!
Opinion: AWESOME! Not only will this help find a Pokemon you're looking for, but maybe you can also use it to EV train!
Registering Overworld Pokemon:
Remember those Pokemon you always see on the overworld Pokemon you haven't gotten yet? Ever wondered why you couldn't scan them and register them in your Pokedex? Well now you can! If you see a Pokemon in the overworld and have the DexNav active, it'll automatically register that Pokemon! You won't be told any info about that Pokemon except for its name, but it will tell you where you can find that Pokemon!
Opinion: This is more of a bonus feature, but still nice to have! The DexNav is more of a addon to the Pokedex rather then the PokeNav! I'm also going to guess any Pokemon registered this way will have their silhouette(if didn't catch one)/icon (if caught one) automatically added to that area.
Overall this is all awesome, it makes collecting really fun! :D