Kitti is half Demon, half Witch.
He has both of his parents powers however he mostly use his witch powers since he fear using his demon powers.
His demon powers had something to do with his trauma.

His demon form vv

He can turn halfway into his demon form when he's having a panic attack or very upset, the only way to trigger his full form is to anger him which is very rare to do.

Tiffany is half Dragon, half Purple Monster.
She has no control over her dragon powers since she never learn how to.

Her Monster form vv

She can turn into her Monster form at will however she can turn if upset or angered.

Zmeya is half Demon, half Witch.
She can use both of her parent's powers, she mostly use her demon powers.
She likes to fly a lot

Her Demon-ish form vv

She can't turn fully into a demon since she has most of her mom's looks, so this is close enough for her.
She enjoy scaring people in this form

Emily is half Yellow Monster, half Gargoyle.
She understood how to use her Gargoyle powers but have a hard time using it.
She'll turn into stone if she got scared, it'll take 4 hours for her to turn back to normal

Her Monster form vv

She can turn into her Monster form at will however she doesn't have very good control of it