Diablo IV will be a full-price game with a Cosmetics Shop and Battle Pass—none of which provide any pay-for-power options.
The standard edition has no pass at all
Deluxe has a regular pass
Ultimate has Accelerated pass
Regardless of which editions you get, you’ll have access to the season pass in Diablo IV.
From what’s been told to us thus far, Diablo IV season pass will include a free tier bar (this tier bar would have all the in-game boosts and advantages to it) as well as the premium tier bar (this tier bar would have only cosmetics and premium currency which is used to buy more cosmetics).
The deluxe and Ultimate editions merely unlocks the premium tier bar for the season (it’s unknown whether it’s merely for the first season or all seasons), so you wouldn’t need to purchase it. The Ultimate edition goes a step further and unlocks up to 20 of the premium tiers within the season pass.
With that said, the premium season pass won’t have any in-game boosts or advantages in it (from what’s been told thus far). Such things will only be available in the free season pass (which is available to all players), and spending additional money won’t unlock said boosts any faster as the boosts can only be acquired by playing the game (But you can get cheap Diablo IV Gold now).
The pass (reg and accelerated) have a free tier with unlocks to free material (I’m using material as a place holder noun for what one gets), but standard does not have a pass. Season Boost is unlocked through the pass, but again standard does not have a pass. The season boost increases XP gain so leveling will be faster, which will amount to an indirect power/advantage gain. Ultimate pass has a faster season boost unlock and some sort of tier skipping which sounds like another indirect/passive power/advantage gain. The ultimate pass’ accelerated unlock and tier skips sounds like a replacement for the group XP benefit in D3.