The creature cards brought to the battlefield with Protean Hulk enter the battlefield simultaneously, since the single action verb "put" is used for this purpose (C.R. 608.2c). Even so, however, if one or more triggered abilities trigger as a result, they will wait until after that ability finishes resolving before they go on the stack (C.R. 117.3b, 117.5) — and if you control multiple triggered abilities waiting to be put on the stack, you choose the order in which they go on the stack (C.R. 603.3b).
But because the creatures are brought in simultaneously, if one of the creatures brought in would, upon resolving, create a trigger for the next creature, that trigger would not go off, correct? For example, if Protean Hulk died and I brought in Lavabelly Sliver and three other slivers, the other three slivers would NOT deal 1 point of damage because they didn't enter the battlefield after Lavabelly Sliver, correct?
RULES OF MAGIC :
http://magic.wizards.com/en/game-info/gameplay/rules-and-formats/rules