ATTENTION: the following diagram and rules are (c) 2004 Jim Aikin and are taken from his webpage Five Up. Note: Jim's 5x5x5 variant sets up the White pieces on the top two levels, thus requiring the White Pawns to move downwards. Apart from this change, his pawn movement rules are the same as those stated in my comment ten days earlier.
Figure 6. The white pawn shown here, which is advancing toward the A5 row,
can make capturing moves to the cells marked 'x' and non-capturing moves to the cells marked '+'.
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
5 |_|_|_|_|_| 5 |_|_|_|_|_| 5 |_|_|_|_|_| 5 |_|_|_|_|_| 5 |_|_|_|_|_|
4 |_|_|_|_|_| 4 |_|x|_|_|_| 4 |x|+|x|_|_| 4 |_|_|_|_|_| 4 |_|_|_|_|_|
3 |_|_|_|_|_| 3 |x|+|x|_|_| 3 |_|P|_|_|_| 3 |_|_|_|_|_| 3 |_|_|_|_|_|
2 |_|_|_|_|_| 2 |_|_|_|_|_| 2 |_|_|_|_|_| 2 |_|_|_|_|_| 2 |_|_|_|_|_|
1 |_|_|_|_|_| 1 |_|_|_|_|_| 1 |_|_|_|_|_| 1 |_|_|_|_|_| 1 |_|_|_|_|_|
A a b c d e B a b c d e C a b c d e D a b c d e E a b c d e
ATTENTION: the following diagram and rules are (c) 2004 Jim Aikin and are taken from his webpage Five Up. Note: Jim's 5x5x5 variant sets up the White pieces on the top two levels, thus requiring the White Pawns to move downwards. Apart from this change, his pawn movement rules are the same as those stated in my comment ten days earlier.