Emboar is not a bad pick for when you’re just playing the game, going through gym leaders. If you can get one with a hidden ability, then you’re in for a real treat when taking advantage of its high attack, decent move pool and STAB attacks. Fire Blitz is going to be your bread and butter as Emboar can destroy lots of ill-prepared Pokemon with Reckless.
However, it’s a slow Pokemon with a speed of 65 and can be out sped by many other Pokemon. Also with such a heavy reliance on Fire Blitz, one of its best fire STAB moves, the attack will eventually take its toll on Emboar. Mix this with a weakness to Stealth Rock, and you’re going to run into problems.
There’s also the fact that, with your Pokemon team, you are limited to how many options you have when putting together a competitive team. Yes, you can pick this fire-fighting type, but why would you when there are way better options. Even just looking at other Pokemon starters, you have both Infernape and Blaziken, whom both have power and speed. Blaziken in particular has the ability to mega evolve which puts it into a whole new category. Emboar isn’t the worst, but it has some really tough competition and some serious issues.