Here's something I considered putting in the "little things that annoy you" thread, or maybe even Unpopular Opinions. Then I realized Game Freak actually managed to do it right in the latest games, so I'll rather commend them for taking action on the issue. Anyway, here goes:
The common implementation of the Pokédex in the games is seriously lacking.
As-is, the Pokédex is a Pokémon encyclopedia, buried too deeply in the Start menu to reflect the stated purpose of the device. Yes, it's at the top of the menu, but you still have to take a break from whatever you're doing to dive into its features. Exit the overworld, scroll through its features, look up its content. In battle, it's not even available, although I don't think it strictly needs to be.
However, in other media (Anime and manga, most notably), the Pokédex is shown to be the trainer's main way of acquiring information on the fly. Dex in one hand, Poké Balls in the other, that's how trainers often battle. It presents information through pictures and spoken text, there's no mention of having to sit down and scroll through menus to be able to use its features.
However, ORAS did it very, very right. Not perfect, but miles ahead of the preceeding games. The DexNav was presented as a PokéNav feature, but in reality it does the job the Pokédex was supposed to ever since we got two screens to play on.
First of all, the information is continuously available. With the DexNav open, you can see what kind of Pokémon reside in the area without having to open any menus. You see what Pokémon you have encountered, what Pokémon you have caught, and whether you've caught all the Pokémon available in the area. A button press takes you straight to the relevant Pokémon's Pokédex entry, if you have it registered. That's exactly the kind of stuff the Pokédex should do. The information you need, when you need it, making Pokémon catching a whole lot easier.
Also, it allows you to search for specific Pokémon nearby, and makes it advantageous to fight wild Pokémon several times. Have my standing ovations for that feature. Yes, it's not a guaranteed encounter, and the implementation could need some tweaking, but it's a really, really neat feature.
Plus it even warns you if there are any rare Pokémon nearby, and gives you information on them before the encounter even begins. The DexNav truly represents a paradigm shift in regards to what the Pokédex should do. Not continuing these features would be a huge step back, and I really hope the DexNav represents the new standard of Pokédex utilization.