Playable characters in Chrono Trigger only have four directional sprites: up, right, down and left. There are no special sprites for diagonal movement.
For example, if you move down and then right, Crono will face down and move diagonally.
You should be able to meet your requirements with the available sprites like this:
Up-Left Diagonal ---> Up
Up-Right Diagonal ---> Up
Down-Left Diagonal ---> Down
Down-Right Diagonal ---> Down
Left-Up Diagonal ---> Left
Left-Down Diagonal ---> Left
Right-Up Diagonal ---> Right
Right-Down Diagonal ---> Right