Well I agree Typhlosion is the better partner for the two, no question. However, if Reshiram decks are as popular here as in Japan, Emboar gives you the edge in the mirror as then your opponent needs a PlusPower every time they want to KO you. It's the same thing against Zekrom - they need a PlusPower to KO you in one turn if you use Emboar.
So while Typhlosion is the better partner overall, Emboar gives you better matchups against two of the most popular decks around (or at least in Japan)
So while Typhlosion is the better partner overall, Emboar gives you better matchups against two of the most popular decks around (or at least in Japan)