I figured it out.

Dipper

Pinetree

He can analyze anything he touches and is super smart and strong. Can share his sister's abilities with their "Twin Link"

Mabel

Shootingstar

She can change the shapes of any part of her body to any animal she can imagine, including their strength. Can share her brother's abilities with their "Twin Link"

Hope these make sense. I'll write more soon enough. Bye for now!