Copycat

All your life you have always imitated more successful people or taken credit for other people's achievements. You are so good at this that you have achieved almost nothing yourself by parasitizing on others. Thanks to this archetype, your skills will depend on your allies.

Class changes:

Expertise:

On 6th level you cant choose expertise from your proficiencies. Instead, choose any two proficiencies from your teammates and get expertise at them. You can change those proficiencies after long rest. 

 

Ability score improvement:

You can improve your abilities as usual, but you cant  choose feats. Instead, choose feat of your teammate. You can change that feat after long rest.

I haven't achieved anything myself

At 3d level, you can choose three proficiencies at armory, weapons, languages or skills of your teammates or choose two cantrips and two spells of your teammates. Instead, you can choose to take one proficiency and one spell and cantrip or two proficiencies and spell or cantrip. You can change them after long rest.

Imitator

At 9th level, you get 3 copycat points. You can use them to copy any action that you saw. For example: a barbarian uses his rage, so you can use your copycat point to store that action for yourself. At your turn, you can use that point to get enraged yourself. It also can be used to store spells, cantrips and so on, but your character should be able physically to do so. For example: you are playing as a human and you see how a giant crushes a person or how a dragon burns everything with its fiery breath. Trying to copy and repeat this action, you only trample the enemys feet or breathe desperately towards the enemy.

Points are always used as bonus action. One copycat point can be restored after short rest or all of them after long rest.

Remember and repeat

At your 13th level, you can use any of your temmates ability modifiers three times before short rest. Also, once before rest, you can copy any dice roll that your teammate made.

Mimic

At 17th level you can choose one more proficiency, spell and cantrip of your teammates. That proficiency, spell and cantrip can be changed after long rest. You also getting 3 more copycat points, and you are restoring 2 points after short rest. Also, before short rest, you can now copy any two dice rolls of your teammates.

At the end, once before long rest, you can copy anything of your size. You are getting looks, abilities, skills, gear and so on of copied object or person. That effect lasting for 24 hours and can not be dispelled. User can end that copying by himself prematurely.