Martial Arts say: Either in an Active or Reactive Turn, a trooper must reach or be in base to base contact with an enemy in order to be able to use this Special Skill. If a Trooper with Martial Arts lvl 1 does a move, provokes ARO, shot in responce, and moves into base to base with the second order he still can apply -3 mod to enemy attacks, because MA do not require melee attacks and just b2b contact?
Not really. It does not work because MA is a CC Skill, and you need to declare a CC Attack to apply the CC MODs of a CC Skill. What a CC! lol
This is correct for the purposes of your question. I'm not going to rehash the arguments of the other threads, but at the very least there hasn't been definitive consensus on if you need to make CC attack for the "Opponent Mod" to apply.
To repeat, although it's not explicitly spelled out, you must declare a CC Attack in order to use the CC Special Skills that are Attacks. This is why i-Kohl has an explicit exception that also allows it's use when declaring a Dodge or Engage.
To be more specific: what is said above is what CB intended to write but failed, getting lost in vague descriptions instead of using defined in-game terminology. But yeah, we had enough threads about it already.