Topic on User talk:Hautarche

Chaos Skip, Skip, and Mass Chaos Skip all achieve their effect through an ability comp shown in the XML as "CompProperties_AbilityTeleport". This has a field called "maxBodySize", which does basically what you expect - you can't target any pawn with such an ability if its body size > maxBodySize. The default value for maxBodySize is 3.5, and since none of these three abilities' XML has a specified maxBodySize, they all use the default value.

Items, lacking a body size value, are not subject to this limitation (even if the object would intuitively be larger 3.5x the typical adult humanlike body size).

CompProperties_AbilityTeleport abilities also cannot target any pawn with the "skipResistant" tag, but the only pawn kind with this tag is the Apocriton.

EDIT: since this is already about psycast targeting limitations, I'll also put the reasoning for Berserk, Berserk Pulse, and Neuroquake being unable to affect mech bosses and Dreadmelds here. That is, all of them have the "isBoss" tag, and those three abilities have "canTargetBosses" set to false; for single-target abilities like Berserk, this makes bosses ineligible for targeting, but for area-effect abilities like BPulse and Nquake, it simply renders them immune to the area effect.