Something to go with a Kricketune deck for younger kids could be Quagsire d (DF) or Swalot (CG), but both of those might have difficult attacks to add up for a 4 yr. old. Try and stick with either something Grass or colorless with fairly simple attacks to understand (Wigglytuff or Dodrio come to mind). Usually the best way to get a younger kid to start playing is to let them pick 2-3 pokemon and build a deck for them based around those. Don't worry if the pokemon don't compliment each other yet, just let her learn how to play and have fun.
A few things I tried with my kids when they first started is building 40 card no trainer decks. This helped them learn the basic concepts of the game (drawing, attatching energy, evolving, attacking). Try and build 2-4 decks like this with easy to use pokemon that are on par with each other so she can play with you or her brothers. Once she gets the basics down add things like weakness and resistance (ignore these when you first start) and add in some simple trainers (switch and potion). Also, reduce the number of prizes down to 3 or 4 to help make the games go faster as little kids tend to lose interest if things drag on. Once she is famailiar with all of that, start adding in trainers in groups of 4 to help them learn what they do (personal favorites for little kids are Island Hermit, TV Reporter, and Prof. Cosmo's or Team Galactics Wager, along with Switch and Potion). Add those 20 Trainers to the 40 card decks you built before and she can then work on getting used to playing with 60 card decks.
The biggest problem you will face is keeping her confidence up when she first starts and when playing with her brothers, as she will more than likely lose much more than she wins.