This kind of talk of "C" ratting would be useful if there were an industry standard... There is none.

I look at setups from an overall vew of my needs.
1/18th, 1/10th or 1/8th scale?
Hot wind high KV motor or soft low KV motor?
Low grip or high grip track?

Buy the best batteries you can afford, but don't buy into the hype of the overpriced ones... (Catch 22 isn't it)

Battery weight tends to go up as the mAh & "C" ratting goes up.
on average 300grams is fairly normal I have seen up to 330g for a 6000mAh pack. Weight is some times a concern.

Just shooting from the hip,
1/10th scale 120amp pack minimum
1/8th scale 150-170amp pack minimum

The mAh of the pack will be dependant on setup & driving style.
Todays batteries are a lot more powerful compaired to those of even a couple years ago.
Some of the fastes guys I've seen drive junk & run clean.

I've done some datalogging over the years & there is some options you can take when it comes to the larger scales (1/8th Buggy & Truggy), but most standard setups for 1/10th scale are sufficent.