Attack Types

White Attack
White Attacks simply hurt you if you collide with them. There is no special way to counter them other than avoiding them.

Gray Attack
Gray attacks are projectiles that cannot harm you. They seem to mostly be for leaving a message. This type of attack is introduced by Napstablook in which it spells out "REALLY NOT FEELIN UP TO IT RIGHT NOW. SORRY." It is also used by Mettaton to spell out "Happy Breaktime!"

Green Attack
Green attacks are projectiles that heal you. Moving your soul into them is necessary to spare majority of the fights where they appear. This type of attack is introduced by Vegetoid, and is also used by Woshua, Tsunderplane, Parsnik, Whimsalot, the Royal Guards, and Flowey.

Blue Attack
A Blue Attack is a game mechanic in which certain projectiles will not harm the player so long as they are not moving. It is the opposite of an Orange Attack. The mechanic is introduced by Doggo and is used later on by Lesser Dog, Greater Dog, Dogamy and Dogaressa, Gyftrot, Papyrus, Asgore, So Sorry, Mettaton, Sans and the colored laser beams found in Hotland and the Core.

Orange Attack
An Orange Attack is a game mechanic in which certain projectiles will not harm the player so long as they are in motion. It is the opposite of a Blue Attack. The mechanic first appears with the colored laser beams found in Hotland and the Core. It is also used in the fights against Pyrope, So Sorry and Asgore.