Pokémon Yellow
Extra Damage
While fighting, select your desired attack. When it says you are going to use that attack (eg. "Venusaur used Razor Leaf"), hold down the A button until your opponent's life stops draining. If your timing was right you'll do more damage than usual.
Credit Goes To: GB Station
 Extra Damage
 Animated Pokémon
 Double Your Prizes
Secret Coins
At the Game Corner there are secret coins lying around. You can get these coins by walking around and pressing the A button.
Credit Goes To: GB Station

Easy Level Gain
While fighting, select your desired attack. When it says you are going to use that attack (eg. "Venusaur used Razor Leaf"), hold down the A button until your opponent's life stops draining. If your timing was right you'll do more damage than usual.
Credit Goes To: GB Station