Your not missin anythin... Literally every game is the same since the original 2. The only difference is every generation theres more and more pokemon which really doesnt matter a whole lot cause its impossible to catch every one from every generation in a single game
He said a pitch, not an anti-pitch.
I could go into full detail about what each generation brought in terms of significant changes to the original "Hard to the Body/Cockfight" model... but I feel it'll just get lost on you since to you, it will seem to you like the same game since GenII no matter what I say.
...so yeah I'm not gonna do that. Instead, I will present the pitch:
-Imagine an odd world where, in addition to regular animal, you have these super-powered up animals called Pokemon. In this world, these little critters have been around since practically forever. There are theories about where they came from (Outer Space is a theory), but most of what Pokemon are and why they are around is a great mystery.
-Pokemon have super-abilities and have been able to use them to help the humans in this universe do everything... and humans have barely been able to understand that these critters also have digital qualities. It is because of this that they are able to be catalogued, analyzed, and captured using digital technology in the capsules used to capture them (the Pokeballs). A Pokemon, upon being caught, is bound to its owner until the owner dies, the Pokemon dies, or the trainer uses a computer to 'release' the Pokemon, at which point it's release into the wild.
PREMISE OF THE GAME:
-The games are aimed at young kids, and are based on the original creator's hobby of insect collecting. Like most collecting games of old (remember stamp collecting, or trading card collecting, etc. from back in the day?), there's an element of trading, which is why they develop opposite colors/metals/etc. versions of each game. However, the premise of "Well this version doesn't have this, while the other version has another thing" is no longer relevant, since the latest titles can more easily connect to the Internet, allowing you to easily trade with anyone in the world. I've been trading when I play at night, with people in Japan and Korea. The latest version (Version X and Y) has gotten so good at the trading that you can trade with strangers almost as easily as with friends.
-A youngster will be tasked with helping a professor gather various amounts of information on each Pokemon. A principle similar to Wikipedia and crowd-sourcing, as every kid collects information, a more accurate picture of the nature of each of these critters starts forming. The reason it's a kid is because of the aforementioned paragraph, about the original creator's old hobbies. In the game, all sorts of characters use Pokemon, whether for hobbies or for practical purposes (a construction worker may use a Diglett to help them dig around, or an explosive pokemon to do controlled explosions, etc.), so although the professor usually has kids tasked, anyone (even your mom, at times) gets to use Pokemon.
-The game is rather open-ended, but has a loose set of rules to balance the game out so that it's not broken right at the beginning. I will go into them loosely:
-1. you can only carry six pokemon with you at any one time.
-2. you can never start out your journey without at least one pokemon (usually given to you by the professor).
-3. trainers who challenge you will give you money upon losing against you.
-4. upon you losing, you lose half of your money and start at the latest save point (circumvented by just reloading your save)
-5. traded pokemon can be used... however, they know your level of skill, and traded pokemon may become unruly and disobey you if you do not have the badges to show that you command respect. Because of this, you cannot just trade a Lv100 Pokemon at the beginning of the game and wipe the floor with people; each badge you earn (usually eight in a game) allows you to control traded Pokemon up to a certain level.
-6. Usually the badge earning is a linear path, and the story usually crosses with that path a number of times, so getting your badges is a linear thing, but collecting the Pokemon isn't.
-7. Some people gather six Pokemon at the very beginning, and raise them and go for the badges, upon which they defeat the "Pokemon League" (usually consists of four high-level trainers) and the "Pokemon Champion" of a region (the last person who defeated all of the 'Elite four' aforementioned members). Still, some others don't focus on the plot at all, and rather want to complete the Pokedex (a play on Rolodex), a list and encyclopedia on all of the existing Pokemon, by hunting for them in different locations of the region the game in which is all takes place. Still, others want to know what the plot is and finish it, and although the plots for each game are similar, there's always some kind of twist to them (the original game had "Team Rocket", a mafia-like organization in Kanto that wanted to use Pokemon for nefarious purposes, but newer games have had other organizations with their own schemes).
-8. Since the earlier generations, new elements have been added that add on to the experience: Perhaps you want to 'breed' the best stats out of a Pokemon... so the game has a breeding mechanic for people who want to do that. Still, some other people prefer to raise other stats that are not battle-related and participate in things like "Pokemon Contests" or "Pokemon Plays" (depending on the game). Different games have different attractions for that sort of thing. Most games these games have some kind of Battle Colloseum/Arena where everyone plays on an even playing field vs. computer opponents, and even if you go there with a Lv7 Pokemon, the game will auto-raise it to, say, Lv50 so that you can compete (moves don't change, though), adding a bit of a challenge element. The most popular thing, obviously, is building up your perfect 'dream team', that you can use online or against friends to battle and win. Pokemon Tournaments are very popular, as a result.
-9. Although the game's plot has the 'ending' being when you defeat the game's regional Champion, the game continues afterwards. Usually afterwards, special attractions will open up that'll allow you to bring in your Pokemon from previous games (using different systems in each game; with DS games you would connect the GBA game to the bottom of the DS, while in the later DS games you would use another DS and use DS Wireless Play, and in the latest games it'll probably be done that way as well from a 3DS to a DS.... think of how Suikoden did it, it's similar).
-10. the trading aspect has been expanded upon now, and even if you 'catch them all', maybe you want all of the 'forms' of each critter (some have different forms, besides the 'male and female' which sometimes also vary slightly). Even if that happens, you also get markings if you get them from different World Regions (so if I trade with a Korean Pokemon I get it marked on my PokeDex). It can be quite overwhelming, but it's all optional.
I believe this is a pretty good crash-course on Pokemon and what it's all about.
Many people don't think it's that cool or whatever, until they actually start playing it and get into their own groove with it, it can be a very worthwhile, addictive experience.