First you will have to set up an event with the conditions for when an enemy can be sucked.
example:
keyboard on space down
system compare two values : distance(player.x,player.y,enemy.x,enemy.y) <= 200
then you should make the sucking action:
enemy set position :
x = lerp(enemy.x,player.x,dt)
y = lerp(enemy.y,player.y,dt)
Then you should have an event on enemy colliding with player.
To make sure the player is sucking you should create an boolean instance variable IsSucking.
keyboard on space pressed: player set variable IsSucking to true
keyboard on space released: player set variable IsSucking to false
enemy on collision with player
player variable Issucking is true :
etcetera... (being what PixelRebirth said)