Melmetal is a pretty good physical attacker/defender. Along with that, it has high HP. However, it does poorly as a special attacker/defender. Plus, its slow. Therefore, it is a perfect physical tank, but won't survive a team of special attackers. Melmetal also has 10 not very effective types and 1 no effect type against it. In conclusion, if you want to spend the time and probably the money, Melmetal is a solid addition to your team. Just be wary that you won't be able to get your Melmetal back into Pokemon GO, and Melmetal will only be available to LGPE, and possibly Sword & Shield.