For me, Yahtzee and i share the same problem. Our pinky finger is useless. Just curious too see how many other people have the same problem and if its possible to finish hard doing so.
What i meant was actually how many fingers for the coloured buttons. And for the guitar only, not the singing or drumming or bass or whatever else you can possibley create

Just one, the middle one. :p

All seventeen of them. It's how it's actually possible for me to successfully play the game.

I can't use any more then four. A sad old sap I am. Easy mode for me is still a challenge.

Usually four fingers, but i've been playing Guitar, Bass and Drums for longer than I could even want to remember. I tend to find it easier with timing and general movement, at the moment i'm practicing finger tapping, when you hold down for instance Green and use your other hand to tap Red, Yellow, Blue and Orange without plucking. I'm not sad! :)

4 fingered salute here. Can't stretch my pinky for bank notes though, so I came up with the idea to practise stretching my thumb for the green.
Took me about 5 seconds to realise Guitar hero really likes green, so back to pinky workouts for me.

My pinky works just great for just about everything but quick note tapping. But that comes from playing guitar for like six or seven years and actually having to use it. So all five.

But I've been spending a lot more time with the drums.

I can use my pinky finger reasonably effectively, but I get confused when I move my hand down the neck, so once I move down to start hitting orange notes, I'm screwed when I have to make a sudden change back to hitting green ones.

Three.

I move them.

Cramptastic, mind.

I use four, my pinky is rather unnaturally strong so moving around is fairly simple for me. I use my forefinger to hit green when its just there occasionally.

11 fingers!*nibbles on bagel*

None

I'm always the singer

All 5. My 'Pinky' is strong from 10-11 years of playing the piano (9" stretch between thumb + little finger), along with 2 years of Guitar. Also, I have a habit of tapping thigs all the time; It really annoys everyone around me.

The 'pinky' is very hard to make strong, so I can see why many of you have a problem, but at least use more than 1!

4 fingers for the colours, moving my forefinger up to red when I need to pinky the orange.

I also much prefer to stand up while I play, gives my less to worry about balancing the awkward Xbox 360 GH2 guitar shape.

2-3 on easy or med
3-4 for hard

i havent even started expert yet (just got it a week ago :O)

None, actually-- I play on expert with my dick.

HSIAMetalKing:
None, actually-- I play on expert with my dick.

The first case of AIDs caused by video games, (Trauma Center doesn't actually say AIDs)

I put the guitar on a table, put my thumb on the buttons and use 4 fingers 1 thumb, sounds gay... I beat it on expert except for raining blood.

I push the fretts with three fingers and move my hand for hard, but I hardly ever go past medium.

When I play Bass on Rock Band I strum with the finger that goes with the frett

I use 3 fingers and play on Expert-level. The reason why - I've learned the technique of moving my 3 fingers across the board. There's never one moment in Guitar hero on Normal Level where you will need 4 fingers at one time. All chords are 3 fingers.

One good way of training your technique is to play the game in Normal Mode, and use 3 fingers only 3 fingers and learn to move the fingers across the board. By the time you learn that technique, it'll be a lot easier in Hard-mode to move the fingers across the board.

Literally all of them. Left hand uses all fingers, and thumb to prevent the guitar from falling (aka 'grip'). The right hand uses thumb + index (only on stupid adjacent notes) to strum, then middle to pinky on the whammy bar when there's star power or I get bored on a stupid long note.

Four fingers

cattypat:
Took me about 5 seconds to realise Guitar hero really likes green, so back to pinky workouts for me.

You might try keeping your hand on RYBO and shifting up to hit Green when you need it instead.

If I want to kick ass, 3. If I want to suck balls, 4.

Six. Four for the chords, two for the strum bar.

play a real guitar to build up those pinkys?

that or learn a new masturbation technique that involves the pinky.

i use only 3. my forefiger hits green and red, and my middle hits yellow, my ring finger hits blue and my pinky hits orange (with great difficulty eve with my pinky only handling one.)

I play at expert level and only use 3 fingers, with the index defaulted on red, and yes for the first couple of goes its all about the cramp but it gets easier with practice... lots of practice.

Four fingers for me. I never really tried to do Guitar Hero 2 on Hard because all the songs I liked were unlocked on Medium so there was no motivation ^^