Slowbro

Mega Slowbro is one of the premier defensive powerhouses in the Uber tier. Its magnificent bulk and decent typing allow it to wall top-tier threats such as Primal Groudon and Ho-Oh. Before Mega Evolving, Slowbro has access to Regenerator and Slack Off, which grants it the ability to switch in and out frequently without being worn down easily. It has a very wide movepool and reasonable Special Attack, which prevents it from being too passive. Slowbro's access to Thunder Wave aids it in shutting down physical sweepers and slowing faster Pokemon for its teammates to outspeed and possibly KO. While Slowbro is a fantastic wall, it has flaws just like every other Pokemon. Its Speed tier is terrible, so just about any Pokemon in the meta outspeeds it with ease. It has mediocre Special Defense, which prevents it from being an all-round wall, so it should not be switching into special attackers. Though its typing provides it with a few resistances, it also leaves it vulnerable to Pursuit, which Pokemon like Tyranitar can take advantage of. It loses Regenerator when Mega Evolving, which, while it doesn't completely cripple it, does force you to play a little more safely with it. Mega Slowbro also hates entry hazards and just about any type of damage that accumulates over time.