Having played against Fiddlesticks in ARAMs recently... I don't understand why the team insists on staying in the minion wave and taking it.
I was Tristana last time, farmed the minion wave from the side of the healths. Stayed against the wall the whole game. Never got hit by Fiddlesticks once when allies were around (only after my 4 allies all died from the constant poke). I also could have easily cleared each minion wave on my own so my allies had no reason to be over there.
The biggest problem with ARAMs is that most people don't understand early game there. There are a lot of champions and teams that need to turtle defensively until level 6, or until 16 sometimes. Against Fiddlesticks, that's pretty much every time. Stay separate and don't let the crows bounce. Don't bother poking him because he'll drain it back. If you're going to attack Fiddlesticks you better darned well kill him (all-in him).