The Move Reminder unfortunately can't be found until the very end of the game, inside the Pokemon Center on Mount Lanakila of Ula'ula Island, right before the Elite Four. If you want to use him to implement a certain moveset strategy, you can find him early on in your adventure inside the Pokemon Center in Hau'oli City on Melemele Island. Inside you're going to find many, many more difficult challenges.With the absence of HMs in this game, the Move Deleter isn't as useful as he once was. Once the pair are defeated, they'll give you access to the Battle Tree.
If you want to face that team down, you'll need to deal with their elevated levels!
Something has dragged them along to Alola - and that means your Pokemon trainer in Sun & Moon can face them down. Those who played Red & Blue back then are quite a bit older - and so are this pair.
Some 20 years have passed since the events of Pokemon Red and Blue - and that goes for the game world of Pokemon as much as it does the real world. Something the folks at Nintendo and The Pokemon Company made quite a big deal out of prior to the launch of Pokemon Sun & Moon was the return of two classic Pokemon trainers - Red and Blue, the original player character and rival character from the original Pokemon.