I am getting some custodes put together, I would imagine that if you were looking to win then I would focus on the units that work towards that.

Your biggest issues, besides the psychic stuff, is mobility, as custodes aren't that quick.
So if I was going to go monofaction I would definately bring pallas and caladius grav tanks, both, as they are mobile platforms which would help with getting good shooting in and not particularly susceptible to close combat.

If you drop the terminators you could take 3 pallas and either another telemon or a caladius. You might have to drop drop one of the banners to do this.

This would give you some mobile units able to hold back or side objectives and avoid scenarios where you might have to leave other units idle. It would also draw fire from your troops towards the vehicles and let your troops advance up the board in better health. Would assume that normally you drop the terminators in to absorb fire, but if they don't last then you would have problems commiting your backline to the battle later, more mobile backline would also allow you to do this.