Only 2 players for online? Easy(er) ways to get "Striker" & "What Happened?" achives
Easier Striker achievement with only 2 people.
Step 1: The one who wants the achievements has to host, and invite the second player.
Step 2: Player 2 chooses the opposing team.
Step 3: Player 1 has to score a goal (the first one, bouncing off one of the other players if going for the "What Happened?" achievement), or player 2 could knock it in their own goal, which will then leave the puck re-appearing near player 2's side.
Step 4: If player 2 holds still, the computer will briefly stagger off toward the bottom of the screen during the restart. Player 1 can rush in and score a goal right past player 2.
Repeat step 4 until time expires.
This tactic can be used for the What Happened? achievement. Player 2 has to score a goal in their own goal. Then subsequently, player 1 can rush in and score goals by bouncing them off the stationary player 2 and into the goal. These goals won't count towards the Striker achievement though.
Hope it helps a little.