Pokemon GO has removed Registeel from legendary raids and has added Regirock, the last of the Regi trio. Regirock, which is unsurprisingly a rock-type Pokemon, should now be appearing in legendary raids worldwide, so players will want to make sure they have the best raid group possible to counter it.

In the meantime, some Pokemon GO players may be wondering exactly when Regirock will be leaving the game so they can make sure they add one to their collection while it's available. Niantic has announced that Regirock will be removed from legendary raids beginning September 20, but the company stopped short of revealing which legendary Pokemon will replace it.

With the addition of Regirock, all of the third generation legendary Pokemon will have been added to legendary raids in Pokemon GO. Considering this, it's possible that Niantic may bring back an older legendary Pokemon for raids, like Ho-oh, Lugia, or the first-generation legendary birds. Alternatively, if the fourth generation of Pokemon have been added to Pokemon GO by September 20, then perhaps we'll see the first fourth generation raid boss next month.

legendary regirock pokedex entry

There are a number of legendary Pokemon still coming to Pokemon GO, but if the next raid boss is a gen 4 creature, then there are seven possibilities as to who the next raid boss is. The possible generation 4 raid bosses that could replace Regirock are the Lake Guardians (Azelf, Mesprit, and Uxie), the Creation trio (Dialga, Giratina, and Palkia), and Cresselia, which is a psychic-type Pokemon with an especially unique look.

Niantic's plans for replacing Regirock should become more apparent as we near the Pokemon's removal date on September 20. However, players that fail to catch a Regirock while it's in legendary raids shouldn't worry about it being gone forever. Niantic has shown a tendency to add legendary Pokemon as Field Research breakthrough rewards, with the legendary Pokemon Raikou currently available through that method.

Another way players can get their hands on Regirock is by trading another trainer for it. Going this route will cost quite a bit of stardust though, unless players trade with someone who they have a high friendship level with, of course.

Pokemon GO is out now for iOS and Android mobile devices.