Nilsson stopped Pearson on a dangerous shorthanded shot just before Vancouver broke the other way for Baertschi's third power-play goal.
The Kings jumped out to a 1-0 lead 23 seconds into the game after Canucks forward Markus Granlund failed to control a pass from defenseman Michael Del Zotto in their own zone. Pearson jumped on the loose puck and beat Nilsson from the right circle for his third goal.
Kopitar made it 2-0 at 3:14 of the first after Dustin Brown found him charging toward the net, giving him three goals and eight assists during his point streak.
But the Kings "took our foot off the gas pedal there," Pearson said.
"We have to look at ourselves," Los Angeles defenseman Alec Martinez said. "We all know the way we can play, and we've done it in spurts. We need to do it for 60 minutes, not 10 minutes in the first period, then back off."
Vancouver tied the game with two goals in 4:50 in the second period. Sedin threw the puck toward the net from a sharp angle, and it struck Los Angeles forward Nicholas Shore and deflected past Quick to make it 2-1 at 5:10. Horvat scored a power-play goal at 10:00 after the rebound of a Brock Boeser shot landed at his feet for an easy tap-in to tie it 2-2.
The Canucks were 2-for-3 on the power play after going 0-for-10 in their past two games. Green shuffled his power-play units before the game, playing Boeser with Henrik and Daniel Sedin, Horvat and defenseman Alexander Edler, and putting Baertschi with defenseman Derrick Pouliot and forwards Loui Eriksson, Sam Gagner and Thomas Vanek.
"We haven't been that great as of late, obviously, on the power play, but every single game I think we did certain things really well," Horvat said. "Tonight, everything just came together. We were really crisp on our passing. And both units were able to deliver."
Quick denied Brandon Sutter on a penalty shot at 14:36 of the second period after Derek Forbort slashed Sutter on a breakaway. Quick challenged Sutter and was preparing for a poke-check when he made the pad save.
Quick has stopped two of three penalty shots this season and four of six in his NHL career.