Pressure? He's already under enough pressure as it is. He's been crowned Pele's successor by the man himself, he is seen as Brazil's best player, and we all know how much pressure Brazil puts on their football team never mind their best player and is known as the best young player in the world. If the pressure hasn't broken him now it never will. Neymar is extraordinarily strong minded, most of us would have crumbled mentally by now if we were in his shoes. In fact, moving to Europe will actually make it easier on him, so he isn't surrounded by the Brazilian press all the time, who pin all their countries hopes on winning the WC in 2014 on him.
Moving to Europe isn't going to suddenly turn him into a frightened kitten, the teams here aren't even that good lmao. People over hype European football to the extreme, but most of the teams are shit, just looking at some of the teams in the CL groups stages over the years shows us this. Neymar will have no problem at all adjusting here, the club which gets him will have one hell of a player in their hands.