Blastoise

On paper, Mega Blastoise might seem like an underwhelming Pokemon due to its average stats, but thanks to its unique ability and movepool, it's a staple in the Battle Spot Triples metagame that's easy to fit on multiple team styles. Mega Launcher combined with Aura Sphere and Dark Pulse make it an effective Special Attacker that can attack any Pokemon, regardless of its position. Access to Fake Out and Water Spout further increases Mega Blastoise's versatility, making it an effective support Pokemon and spread attacker. Furthermore, Mega Blastoise's mediocre Speed allows it to fit well on both Tailwind and Trick Room teams, and its typing makes it a great choice for rain teams.

Mega Blastoise's biggest flaw is that compared to other Mega Evolutions, it actually isn't that powerful. Its reliance on placement-ignoring attacks also makes it extremely vulnerable to redirection. Overall, Mega Blastoise isn't the most prominent Mega Evolution in Battle Spot Triples, but its unique attributes make it an indispensable part of the metagame.