Since the beginning of Pokemon, there have been sites designed to help players with their games. Some famous ones, such as Serebii (which I use a lot) and Bulbapedia (Pokemon Wikipedia) help by explaining central concepts, such as EVs (and EV training), a list of complete Pokemon and their abilities (if more than one), etc. Serebii focuses more on archiving everything Pokemon-related, such as chronicling the Pokemon TV seasons, the comics/manga, Pikachu-related short films, and much more.
Gamers use both Serebii and Bulbapedia to help with finding strategies to catch Pokemon. Serebii lists, the Capture Rate, but does not explain this. If you go on Bulbapedia, however, it will give you the definition of Capture Rate, which is the chance of using a regular Poke ball on that Pokemon in the wild (and catching it). The lower the number, the less chance there is.
For example, the Capture Rate of catching Zekrom, which I looked up after I caught it (with 2 Ultra Balls), was 45, or 5.9%. I wouldn’t suggest only using Poke balls, because the wild Pokemon (especially legendaries) are bound to run out of moves, and will be forced to use Struggle, which will take out 1/3 of their max HP, thus making themselves faint if you got them to a very low HP. The total EXP at level 100 is also displayed on any Pokemon’s info page. Both list a number varying from 600,000 to about 1,640,000, but only Serebii classifies the amount of EXP. Specifically, 600,000 is classified as the fastest, or “erratic”, and 1,640,000, the slowest, or “fluctuating”.
The Pokedex as displayed on Serebii shows only basic information for the game, and is divided into each Generation to help players playing those certain games. Bulbapedia’s articles are actually extensive, and all the information of the Pokemon are listed on its page, such as previous game appearances, TV (show) apperances, random facts about it, and name origins. You can compare Bulbapedia to Wikipedia, since information is lined up in a way quite similar, and its motto is “the community-driven Pokemon encyclopedia”, meaning anyone can edit it, provided they are trusted sources, much like Wikipedia. It also goes in-depth in the Pokemon’s description, explaining something more to that Pokemon than just the Pokedex entries from the game.
Although it would be great to go out and explore on your own, there are experts (dedicated Pokemon fans) that decide to “extract” the game data out of the game for you, so why not take advantage of it? The pages about Pokemon reveal nothing about the storyline of your game, so there’s no worries of a spoiler alert (on Bulbapedia, they have a banner stating a “spoiler alert” for your convenience). Both sites are great for catching up on Pokemon episodes you forgot you watched, or just summarizing for episodes you can’t find. No matter what your purpose is, these kinds of sites will satisfy.
By the way, there are many more sites like the ones I have mentioned, plus other fansites you can take a look at and remember the glory days.