Former Stoke and Crystal Palace manager Pulis will watch from the stands when the Baggies go to West Ham today and is expected to be confirmed as their new head coach before the weekend.
It is understood he will sign a two-and-half-year deal to replace the sacked Alan Irvine.
Pulis will be Albion’s fourth head coach in just over a year and Morrison knows places are not guaranteed.
“You’ve got to impress the new head coach to get in the team,” he said.
“We’ve got a big squad here, a lot of new players came in at the start of the season who are champing at the bit to play.
“So you’ve got to be on top of your game to get in the side.”
The Baggies are 16th in the Premier League, a point above the drop zone, after seven defeats in their last nine games. The 2-0 loss at Stoke on Sunday ended Irvine’s six-month reign, although the Scot retained the support of the players.
But he won just four times in 19 league games and Scotland international Morrison admitted they must move on.
“It’s never easy to see a head coach go. Every week you give your all for the head coach and the bond with the players was strong,” Morrison said.
“You could probably see in the performances that we were all trying our hardest, the club have made a decision and it’s time to move on.”
Sam Allardyce, meanwhile, would not prevent his players from “making a meal” out of contact if it meant his West Ham side were given the decisions they deserved.
“As long as it’s not simulation — as long as you get the right decision from it,” he said when asked if a player needed to fall over to get a foul.
“If you’re not touched and you go down because you’re not touched, that’s not the way forward. But if you can’t get what you ordinarily should get, then you’ve got to consider the fact that if you make a meal of it, you make a meal of it because the contact is sufficient enough.”