Rivals' Week brought some new features to Pokemon GO, and the major ones were the additions of Clawitzer and Dragalge. Both Pokemon are available for the first time since the Kalos region was released in Pokemon GO.
Calwitzer itself is a Water-type Pokemon, and it's the final form of Clauncher. To get Clawitzer, Pokemon GO players need to catch a certain amount of Claunchers in order to evolve the Pokemon. In total, it takes 50 Clauncher candies because there is only one evolution of the Pokemon.
Each catch is worth 3 candy and an additional 1 if the Clauncher is transferred. That means nearly 17 Clauncher's need to be caught for a Clawitzer if only the catch candy was added. However, Pinap berries can double that amount to 6 candy each, and the transfers will pad that as well.
How to find Clauncher and evolve it into Clawitzer within Pokemon GO
During Rivals' Week in Pokemon GO, Clauncher will be roaming around in the wild along with Skrelp. There is no surefire way to find them, but using an item like an incense will increase the chance that they spawn around the player.
Lures at a Pokestop serve the same purpose and can also attract a Clauncher. Walking around populated areas with plenty of stops is the best bet for finding Clauncher in the wild and getting enough candy for a good Clawitzer.
Clauncher will also appear in one-star raids throughout the event, and most players can take one down by themselves. It's an easy way to guarantee a Clauncher and some candy but that also means plenty of raid passes need to be used. A mix between raids and the wild in Pokemon GO should be enough for a Clawitzer.