Twilight's story appears to be broken. After agreeing to help Spike, you become stuck with nothing to click on.

Rainbow Dash, you need to ask Trixie for wings, fly up and win the race.

Pinkie, you need to get the ball from the field, ask Mrs. Cake to wrap it, then place the gift in the upstairs room. Return to the room the next day.

There doesn't seem to be any way to get past the royal guard.

DJ-PON3 is sexable just by walking into her room and clicking on her.

For Trixie, you need to have a unicorn horn, you need to have read the book in Twilight's room about breaking magical shields, and it needs to be nighttime.