This app was mentioned in 5 comments, with an average of 2.00 upvotes
I've used it to play against myself too, just to get a feel for brand new ships or lists I've never flown before.
Also if you're lazy like me and don't feel like looking at an AI chart for determining TIE moves, there's also an Android app that handles much of it for you.
X-Wing AI - Aturi Cluster is similar to the Mark 13 app that /u/eunoiared mentioned for freeform skirmishes, but instead mirrors the HotAC AI, and even lists the specialized behavior for each ship type.
Probably this one. Its not perfect, but it still saves time in randomizing and determining enemy ships movement.
In the meanwhile, this exists. Its not perfect, but works well enough for me.