As someone whose actually finished Let's Go, don't buy the ball as a controller. Don't get me wrong, I have one, and I'm glad I do, but for the switch game, the ball loses nearly 25% of menu functionality. Any shortcuts put into the menu are useless with the ball. Not to mention the select button is clicking in a joystick which constantly makes you pick the wrong thing any time your hand is out of place. Also you can use pokemon from Pokemon Go in the game as normally caught pokemon. Also just because catching works in handheld hardly gives it a pass for docked. Come back after you catch the birds who fly all over the damn place.
It's a great game, and I recommend getting it if you like pokemon, or are curious of what all the hype is about. Just probably take this segment with a grain of salt. It's good, but it has plenty of issues.