Honestly, as I'm remaking my game, when in doubt, I pose the question, "what would a nationally top ranked U12 player do?"
He's obviously accomplishing more than me with a far weaker body, so he must be doing almost everything right.
Also, I think you're misinterpreting (or I am). The green ball is the standard ball. You mean "should they be using red and yellow balls until they are as good as these players?"
They should use them until they become solid. Being as good as those kids with an adult or adolescent body is quite a high level of play.
[K]Six.One Tour (3) 367.5 grams 31.7 cm balance.
Mains: Babolat/Wilson Natural Gut @ 23 kg // Crosses: Luxilon Alu Power Rough @ 21.5 kg