Are the following sentences acceptable?
(1) However, Jilly was unwilling to share her robot dog with her brother, so he decided to make a fool of her.
(2) He hid himself behind the sofa and waited for the chance to tease her.
Grammatically, they are okay.
I don't know how natural it is to think of a child wanting to "make a fool of" someone. Perhaps he wanted to "play a trick on her."
I'm not a teacher, but I write for a living. Please don't ask me about 2nd conditionals, but I'm a safe bet for what reads well in (American) English.