Mega Blastoise

The first Water-type Mega Pokemon introduced in Pokemon Go, Blastoise brings the big guns to any determined player's team. While it's not the strongest Water-type, the boost that Mega Blastoise provides to raid attackers is highly valuable. And yes, Blastoise with sunglasses from its Community Day can mega evolve! Though the glasses disappear while it's mega evolved....

In terms of actual viability, Mega Blastoise is very bulky, meaning it will be able to stay on the field and provide its mega boost to other Pokemon for a fairly long time. In larger groups in particular, this can make bulky Mega Evolutions more effective than high-DPS options due to the sheer power that it grants the entire team. However, in most cases it's a worse Mega Swampert, which itself is a worse Primal Kyogre. I guess that some things just never change for poor Blastoise....

Best PvE Offensive Moveset

• Water Gun sports higher EPS and better synergy with Blastoise' best charged moves, therefore it is marginally better than Bite.

• Hydro Cannon* is objectively outstanding. Don't bother with other options.

• Hydro Pump is Blastoise's optimal non-exclusive charge move.

• Ice Beam has its select advantageous matchups.

• Flash Cannon is an awful 1-bar charge move, and Skull Bash isn't useful either.
• Return offers nothing of any value.