Briar is surprisingly good with children (she has experience after taking care of two kids...), so she could probably try to pacify a crying child LOL

Odd would attempt to calm them down/make them laugh, and then afterwards attempt to locate their parents (typically by having the child look in a different direction while they try to pick up on their parents' energy signature, popping his head through a portal to their area and quickly letting them know what's up with their kid)

Balei taking care of it, trying to calm it down and singing it lil lullabies, she’s a mother after all!

Fausto is both trying his best to keep them happy by buying them ice cream and stuff and also being angry at whoever left this small child alone

Tyler is surprisingly good with children (He's the oldest of 3 so he has experience), so he would first make sure the kid is unharmed. Then he'd joke around and would even let the kid play with his Shiny Eevee while his Dragonite scouts for the parents. He'll be a kind supportive big brother kind of figure

Ruth: Trying her best to calm the kid down, except Ruth talks to children the same way she talks to adults
Kingston: Letting the kid play with Calcifer while he figures out where their parents are

To varying different degrees, adoption

Already answered (https://retrospring.net/@Izetarion/a/109090583407181395)