Cameos
These two popular characters play no significant role in the game
To find Link return to the Rosa Inn same place where you played with that Gaz girl after you find the 2nd star Hell be upstairs sleeping in the bed Try to talk to him and the Zelda Mystery noise plays
To find Samus go to the Mushroom Kingdom after securing the 5th star Go into the castle then to the guest room Samus will be sleeping in the bed If you talk to her she says shes resting for Mother brain
Secret boss
First go in Moleville in the top left house and purchase Fireworks for 500 Coins Sell the Fireworks to a little girl surrounded by crates for a Shiny Stone Now go to the sealed door in Monstro Town and use the Shiny Stone Press A on it