I taught my student, 4th grader Anthony C. the opening system of The Lion for Black. It starts as 1...d6 2...Nf6 3...Nbd7 pretty much no matter what white plays for his first three moves. It can be used against 1.e4, 1.d4, 1.c4, 1.Nf6, or 1.b3 & 1.b4.
He used it for the first time and played it very well into the middle game even though he lost in the end. I thought it instructive and wanted to show the readers so they may want to try it themselves.
Here is the game: