He has a son/nephew named bowser jr., aka baby bowser. Bowser is considered king koopa so he is either just the king, or they are his relatives (how does bowser produce the koopas? *shudders*).
Related as in cousins or brothers, no. They are not related at all.
No, baby Bowser are Bowser when he was a baby, Bowser Jr are Bowser's son.
you only get dry bowser. bowser jr and bowser/ /not golden bowser
If you have NSMBDS, and you beat Bowser in World 1, you will see that when you hit the switch, Bowser falls into the lava. This is how Bowser becomes Dry Bowser.
The key from Bowser in the Dark World allows you to unlock the basement door. Once you have unlocked it, you can access the Vanish cap, and the Metal Cap. (see related questions)
No bowser is not a Pokemon therefore bowser cannot battle a wild BOWSER.
Bowser Jr. puts Dry Bowser into a big pot filled with purple chemicals that somehow not only turned Dry Bowser back into Regular Bowser, but also makes Bowser bigger.
you can't get a bowser costume anywhere, but Kirby can suck bowser up and get a bowser cap.
Bowser
They are not Bowser's children. They are actually Bowser's servants, of which Bowser has hundreds of.
Mell Bowser goes by Mell Bowser.
Bowser's signature symbol is a red Bowser face laughing.