We fought a Mezzoloth (MM, p. 313) last game and in the same turn he could use its Teleport action and then attack, or use magic (like dispel magic) and then attack. As I understand from the Monster Manual, a monster acts like a player character, and I can't see from the monster statblock how it could do both of those actions in the same turn (nothing is listed as a bonus action or whatever else).
Is this a correct interpretation of the mezzoloth's teleportation ability?
Our DM said the teleport was part of his movement, but I can't find any documentation about that. I myself want to start a D&D 5e game in the future, and I'm fairly curious about how to play monsters.