here are their reactions.
Twilight: D…Dear Princess Celestia..I learned that m…my feet are way too ticklish!!! HEHEHEHEHE!!!!
Rainbow Dash: BWAHHHAHAHAHAHA!!!!!!! OH MY GOSH!!! I CAN’T TAKE IT!!!!!
Rarity: NO!! NO!!! NOOO!!! Not the feet!! anything but my feet!! HAHAHAHAHA!!!!!!!!!
Pinkie Pie: I may enjoy laughter, but this is pure torture!!! HEHEHOHOHAHAHEHE!!!!!
Applejack: A’h must not break!! but ma feet are soooo ticklish!!!
Fluttershy: HELP ME!!! SOMEONE!!! KEKEKEKEKEKE!!!!!!!!
Here are their shoe sizes and footwear. FYI you can see what their footwear actually looks like in my previous tickle torture pics involving the mane 6.
Twilight: 8 Black Short Boots and black socks.
Dash: 9 1/2 Blue and red tennis shoes and black socks
Rarity: 8 1/2 White high heels
Pinkie Pie: 9 Brown Flip Flop sandals
Applejack: 10 Brown Cowboy boots and white socks.
Fluttershy: 7 1/2 Yellow flats.