Is there a hidden master ball in Pokemon ruby in prof birch' lab?

Answer 1

At Lilycove, head to the beach and go all the way north onto the small

strip of land. Surf east and you should see a small cave entrance.

Enter it to be in the Secret Base. Surf north to get on dry land. Here

defeat the Grunt and go through the door. Step on the left teleporter

and make your way through all the teleporters, making sure you fight

all the Grunts to gain experience. Eventually you'll reach a submarine

with an administrator. Defeat the administator and the sub will take off.

Once you're done with talking, head to the teleporter you

didn't take, you'll be back at the start. Head into the left teleporter,

then head through and onto the teleporter below you. Maneuver through

some more teleporters to find four Poke Balls. One is a Nugget, two are

Electrodes, and one is the MASTER BALL.

That is the one & ONLY Master Ball in the entire game, there is no "secret" one in Birch's lab, or anywhere else.