I am not sure if there is any we had missed.
I have a feeling there was a couple more.
And there are
Here's a list:
Winter Olympics - wears his swimsuit underwear
Down on the Farm - wears a farm hat
Gadget at the Circus - wears a clown suit and a lion tamer suit
Health Spa - wears his blue training suit
The Boat - disguises as an old man and undresses his coat to reveal his underwear
A Star is Lost - wears an hospital pijamas
All That Glitters - wears his camping pijamas
Movie Set - wears a warrior helmet
The Invasion - gets with paint over him
The Infiltration - wears his disguise
Gadget Goes West - wears his cowboy hat and boots
Launch Time - wears an astronaut suit
Bermuda Triangle - gets covered with oil
Dutch Treat - gets with flour and chocolate over him
The Great Divide - wears his scarf and blue training trousers
Doubled Agent - wears his bad guy desguise
King Wrong - wears the king's jacket (and don't forget the king himself since he's equal to Gadget)
Pirate Island - wears his vacation suit
Luck of the Irish - wears his blue pijamas
Prince of the Gypsies - wears a gypsy scarf
A Bad Altitude - wears his pink pijamas
Dry Spell - wears his blue swimsuit
Weather In Tibet - has his pink apron on
Unhenged - wears his blue pijamas
In Seine - there's a minute where he doesn't have his jacket on
School for Pickpockets - wears his oil color swimsuit
The Great Wambini's Seance - covered with a towel and has a shower cap
The Incredible Shrinking Gadget - wears his pink pants
Tryannosaurus Gadget - his pre historic great grandfather
Gadget's Roma - his roman great grandfather
Gadget's Clean Sweep - his England great grandfather, and wears an yellow jacket
Gadget and the Red Rose - gets with a watermelon over his face
And that's all I can remember
And That's nothing compared to my little sister's wardrobe.