Differences between Pokémon games (7 yr old kid)

Usually a pair of games is released, then a few years later a new pair of games is released. Scarlet and violet are the latest games so if you're looking to get him something he may be able to relate to his friends more on that would be best. Both games are basically the same, but there are minor features in each game that differ slightly to make each a bit unique.

The ones that don’t have 2 releases at a time are different formats. Like Arceus.

For his first game, I’d stick with the 2 release games (sword/shield) etc.

Switch has several remakes of old gen games (like Pearl/Diamond)

Sword/Shield and Scarlet/Violet are the “new” mainline entries for switch. I’d stick with one of those 4 for his first game just so that he can talk “new” Pokémon with his friends. Then you can branch out.

Source: I was you last year.

***** MAKE SURE YOUR KID CAN READ WELL****

I know you said your kid is 7, but make sure he is a strong reader. Pokemon games are 100% dialog boxes with no voice acting. So from the story to the objectives to the battling and the pokemon themselves, everything requires a fluent ability to read before the child will be able to play Pokemon.

Outside of that everyone else has already explained which Pokemon game is which and how they are named. Scarlet and violet are the same game but with just a few minor differences like colors and a handful of pokemon that can only be found in that game. The whole point when the very first pokemon games came out was to catch them all, but the individual versions didn't have all of the pokemon on them. So to get all the pokemon you would have to trade your version exclusives to your friend with the other version exclusives. It was a way to get kids the work together and play together to catch every pokemon.

Would recommend either Scarlet or Violet first, and then either Sword or Shield if they want another one.

For Scarlet/Violet and Sword/Shield, the biggest difference to a 7 year old is which Legendary is exclusive to that title. The one on the box is the one you'll get, so for Scarlet/Violet if the red one looks cool get Scarlet, if the purple one looks cooler get Violet. Same with Sword/Shield - one of the dogs has a sword in its mouth and one of the dogs has a shield head. Whichever one of those looks cooler is the one to get.

If they get super into it by that point, Arceus is a good place to go next. Unlike Scarlet/Violet and Sword/Shield, you aren't trying to get badges to compete in a championship. You get yeeted into the past and have to help explore the wilds and catalogue Pokemon that have never been catalogued or studied before.

Brilliant Diamond/Shimmering Pearl are a remake of the original Diamond and Pearl on the DS, and they're fine but probably a little harder than the others I've already mentioned. These are another 'get all the badges / save the world / become the champion' story.

Let's Go Pikachu/Eevee are sort of a remake of Pokemon Yellow, but you use the joycon stick to throw the pokeball with the motion controller. They were trying something new and different with this and it's kind of weird, the parts of it that were okay were later done better in the games mentioned above.

I did want to point out the they are doing sales on the Nintendo e shop so I’d go check and see if any of the Pokémon ones are on sale.

I didn’t look, but get the emails.