So out of the 4 or 5 lessons I did take in the beginning, I was first taught how to hold a power chord.

Unfortunately it was pointer finger with loads of stress on the ring finger.

 

I am not talking the typical 2 string power chords but the 3 string ones.

 

Its a very bad habit and although I do know how to play using my pinky it is often harder albeit clearer sounding.

(i have boxers fractures on both pinkies, left and right..one was a stop sign and the the other was a dudes jaw. That's a story for the campfire LOL)

 

Is there a song where I can "train my fingers for battle" per say?

(lots of 3 string power chords)

 

It is not necesarilly wrong if you use fingers 1,2,3  (index,middle,ring) on left hand to do power chords unless it hurts, if it does hurts change the position to a more comfortable one.

 

Tina S does a lot of power chirds with 1,2,3 fingers

 

There is lots of power chord in metal songs like metallica does (in the early tabs, never tried their songs in rocksmith though), or megadeth... You'll find tons in punk songs too. You may also work folk things with barre chords : you'll learn several ways to play power chords - which are kinda easy barre chords. From there you'll find there's several valid fingerings to play power chords, and use the one(s) that suits you better depending the context of the song.

Power Metal has power chords. Try out some Iron Maiden, Sabaton or Powerwolf. To be specific, a song that has tons of three finger power chords would be Powerwolf's "Armata Strigoi" which is available as CDLC on this site.

Rise Against has TONS of power chords and octave chords, they are in E flat though, i dont know if you want to tune to that. They are a punk band btw. Awesome stuff and not hard at all (they do have some hard songs though)

Also, its not professional advice but when i wanted to switch over and do octave chords with the pointer finger and pinky rather than pointer finger and ring finger which i played them initially, i just made myself practice one one song only and whenever i would instinctively use pointer finger + and ring finger, i restarted the song. In 3-4 days pointer + pinky came naturally to me and now i do it that way automatically

megadeth would be a great way to learn power chords and at the same time spider chords 

Zombie thread but Ill reply on the off chance OP sees.

 

I broke my left extreme metacarpal years ago and for over 20 years have lived with a metal plate in my left hand.

 

I know your pinky pain.

 

I initially would practice a bit and stop wjen my pinky hurt, after discovering RS last year I began playing longer and longer, barres hurt for me as well as anything requiring pinky dexterity. After a few weeks of playing till it hurt I noticed 3 things, the first being I could play longer before my pinky began to hurt, second dexterity in my pinky had improved, third was that overall movement in my pinky read everyday use and flexibility in my pinky have been improving more than the physical therapy they had me doing.