There's no Coin Case, Bike, or Fishing Rod in Pokémon: Let's Go, Pikachu! and Let's Go, Eevee!—so stop looking for them
In Pokémon Red and Blue, trainers could grab a Fishing Rod to capture Water-type Pokémon and use a Coin Case to gamble in the game area in Celadon City.
If you're looking for these mainstay items in Pokémon: Let's Go, however, you might be a little disappointed.
These items have been removed from the game to reduce the gambling aspect in Pokémon titles (Coin Case) and because of a new capturing mechanic added to Pokémon: Let's Go (Fishing Rod).
Instead, the game area in Celadon City now prompts users with text boxes about games on the systems. Players of the original games should know that the area was used to get Porygon in-game, but this Pokémon is now a rare spawn in the wild on Route 7.
As for the Fishing Rod, the mechanic is pretty irrelevant in a game that has Pokémon freely roaming around for all to see. If you want to catch Water-type Pokémon, just use your Partner Power to surf on one of the oceans instead.
As for the Bike, it has been replaced with the option to instead ride Pokemon, which give you a much-needed speed boost while you travel. Some of these ride-able Pokémon include Arcanine, Rapidash, and Charizard.