Copy is a fan-made keyword introduced in StardriveTrumpeter's Booster 1: Dawn of the Multi-talented Gang. It allows a card to copy a skill from either its allies or foes alike.
Rulings[]
It should be noted that there are some notes for copying:
Q1. The copycat is a grade 2 or less card. What are the skills that it can/cannot copy?
A1. Some skills that can only be used at VC still can be copied, but not all. Also be noted that on ride/call skills are impossible to copy. Example: A grade 2 or less card can copy VC only skills like "Auto {VC} (Choose one of your rearguards and retire it) When this unit attacks a vanguard, you may pay the cost. If you do, this unit gets 5000 power until end of battle." Of course, needless to say, skills like "Auto {RC} When your vanguard Legion..." can also be copied. Regarding to skills that cannot be copied, they were Limit Break, Legion and Stride as if they can be copied then the gameplay will lose its balance.
Q2. The copycat is a grade 3 or greater card. What are skills that can/cannot be copied?
A2. Again, this is a very good question. Although it's obvious that RC only skills are impossible to copy, there are exceptions. Something like "Auto - {RC} During your turn, when an opponent's rearguard is..." can be copied. It should be noted that if the copying skill is a limit break then it cannot copy Legion skills while Legion-sourced copying can still copy limit break and other Legion skills, provided that they don't use some cards of specific sub-clan, that is, something like "Act - {VC} (CB/SB2 - cards with [Sub-clan name] in its card name)" or "Auto - {VC} (Choose 3 of your rearguards with [Sub-clan name] in its card name and...)" are definitely impossible to copy, as the copycat may not belong to a certain sub-clan.
Q3. How long will the copycat get the copied skill?
A3. It is always until the end of the owner's turn.