First thing you want to do is make sure DI is not triggered on Pathfinder. When he dies, he gives other allies TM and Speed Up buff. This helps them get a turn faster and drop DI. I recommend applying DI on Princess Leia because she's going to be immune to the stun from Guard and the first action she will take is her stealth, so she isn't going to delete any unit whatsoever.
Do not use Starck. Or if you do, don't have his unique with a Zeta, he will most likely be your fastest IT unit (Other than Gideon) and he WILL remove TM faster than the enemy gains it even on basic-only auto.
Once every enemy unit except for the one with DI is defeated, use only Auto Basic (Except Piett, if you have him, use his Inevitable Failure)
Whatever you do, do NOT use Piett's AoE ability, it will dispel speed up on the enemy and make their turn progression much slower as a result.
