Okay, apparently the resistance works by him not having his body moved... but what kinds of attacks? Is it just physical movement? Telekinesis resistance? Perhaps even teleportation resistance? You would need feats of him being able to resist those.
That being said, the most common thing Four and Two have done is BFR, with the former's activating either through snapping to lift the target up with telekinesis to lift them to the Big Rotating Building or thinking to send the target into his EXIT [A pocket dimension inside of his body], while the latter's BFR activates through either covering their target from their view with any part of their body or pushing them back with their telekinesis to teleport them to some upside down building in the clouds located an unknown distance away [But far enough for them to never come back]. I see that Thales has no resistance to BFR, so he's going to be out of the picture pretty easily.
As for Edelgard, like I said, you need feats of her resisting these types of BFR, because "Unit cannot be moved" sounds a bit vague as it may even exclude certain other forms of BFR. That being said, even if you do say she resists all forms of BFR, there's nothing stopping Four from just knocking her unconscious by screeching into her ear.
I assume what Edelgard and Thales do is completely random due to their nature as being RPG characters, but at least Four and Two have common leading moves in their series. That being said, the algebraliens should take this low-mid difficulty.