e4 c5 Nc3 Nc6 Bb5

If you are looking for information on the line, Bryan Smith has a lecture on it somewhere here on chess.com. It's been a popular sideline so I'd check recent games in the data base to see what current thinking is.

Found it (edit):

https://www.chess.com/article/view/the-anti-sicilian-without-a-name

Precisely. It makes 2 ...Nc6 a bad move for black unless you have something very good against the Rossolimo or pseudo-Rossolimo or are happy with a draw.

It's inflexible. Doesn't suit my preferred style of play in the Sicilian which is to build up very methodically and to be ready at all timees to exploit a small inaccuracy by means of tactical play with pieces or with pawns. So in an open Sicilian or where it has potential to remain open I don't wish to play either d6 or Nc6 because neither suits the combination of positional aggression which I like. The moment it's looking like a closed Sicilian I like to play d6 unless d5 is a better objective to play for.

It clearly isn't a matter of whose "fault" it is for losing. It IS a matter of develpong one's preferred style of playing the Sicilian to maximise chances of a win against 1. e4. For this reason not many people say around 2000 FIDE who know how I play liked to play an open Sicilian against me, Just like they didn't want to play a Modern Benoni, though these days I'm left behind in theory with the MB and don't trust it any longer. From either side really. I think I may switch to systems with g3 as white.

But you shouldn't be talking about "whose fault" in relation to someone who was learning chess and to the problems they may face or have faced in trying to maximise their win rate early. That's extremely important if you're learning because it means you face a higher standard of player as your rating rises and then you learn even faster. OK?

FROM THE ARTICLE
"One of the downsides of this system is that it is not always possible to reach it. After 2.Nc3, depending on which kind of Sicilian Black is trying to reach, he might play 2...d6, 2...e6, 2...g6, or 2...a6 instead. Nevertheless, each of these have their downsides and each restrict Black's choice in the event that White reverts to the Open Sicilian.

For instance, if Black is trying to reach a Najdorf then he would chose 2...d6, which would allow an "improved" Grand Prix by 3.f4. Alternatively White could go back to an Open Sicilian by 3.Nge2 followed by 4.d4, as I have usually done.

On the other hand, if Black wants to play a Sveshnikov or Kalashnikov Sicilian, then 2...Nc6 is the only way, and Black cannot avoid the 3.Bb5 line. This works very well against such players."

Perhaps not very honest. He doesn't seem to tell us how he can exploit 2. ... e6. 

This was my impression of the position. The engine thinks its equal, but if black wants to claim that advantage he's pressured into playing a very predictable, algorithmic response. White isn't being challenged, he controls the game and is scoring very well online here, about 10% higher than black. The deviations score poorly for black, too, and there aren't many interesting ones. I'd probably respond 3... g6 if I played it. But I'd much rather play 2... e6. It allows for d5 against the fiancettos immediately, it's excellent against the Grand Prix, Bb5 can be avoided... whites best is to transpose into the open lines.

It's typically our fault when we lose a game, but a large part of choosing an opening is accounting for the human factors that may or may not lead us to lose. Which means, among other things, considering what type of player we are, and what our aspirations are.
If I aspired to be a high ranking chess master, or to play alot of OTB games, I would have to think very carefully about the objective soundness of the repertoire... (I suppose. many pros actually play dubious lines). That'd also involve studying the repertoire precisely and deeply. But if that's not my goal as a player, and I don't play on studying extensively, I'd rather avoid lines where white controls the game, regardless of their objective evaluation. So, different values lead you to assess lines in different ways.

I pointed out that it's equal so it was a bit of a redundancy to point out that it was my fault I lost. Chess isn't fully worked out yet. The position looks about even but where black has reduced chances to win, typically white can pursue positional plans in greater safety. It makes 2. Nc6 a bad move because it increases white's chances of a win even though a position is techically level.

i dont think there is established idea about black's best second move after 1.e4 c5 2.Cc3.

Just play the move which transposes to the sicilian u want to play, because don't forget : white could go for an open sicilian next with Nf3 and d4.

2...Cc6 is the move if u play sicilians with 2...Nc6 : Sveschnikov, Kalashnikov, accelerated dragon, classical...

Najdorf players should play 2...a6 or 2...d6.

Paulsen/Kan players should play 2...e6

Accelerated dragon players have a choice : Nc6 or g6.

Just chose the move which fits to your repertoire.

I normally play the Paulsen with a 2. a6 move order. A lot of people avoid the Open with 2. c3.

2. c4 is gaining popularity as it also did in the early 1990s if I remember right, Ray Keene preferred it and then redacted and preferred 2. c3 and then went back to 2. c4. I think 2. c4 is slightly superior. I like playing against the Alapin with ...a6 and I'll play a quick ...e6. The c8 B normally goes to d7 and the N to c6.

After 2. Nc3 I occasionally play a6 but I tend to prefer 2. ... e6. That's because 2. ...a6 can attract 3. g3, Typically against that I like to expand on the Q side with Rb8 and b5 without playing a6. Someone who prefers e6 Sicilians typically likes his pawns nice and flexible. I might play f5, g6, even h5 and g6. Could be d6 or d5 and b6 or b5, perhaps with a6 a5 and Ba6 in some liines. I don't want my pawns messed up even though I don't really like the b8 N. It can be a very effective secret weapon though. Unpredictable, positional and tactical play against e4 requires the minimum number of doubled pawns.