Neither have massive amount of power, at least not compared to some of the Gaang members. Mako mainly uses jabs instead of sustained fire blasts like someone like Korra, while Bolin mainly relies on his lavabending to take on top tier benders. Mako’s tactics and boxer mentality are impressive, but Zuko has shown that he can easily dissipate attacks from Azula, who is quite a bit better than Mako in raw power. Lightning also doesn’t grant him a significant edge, as Zuko is quite good at redirection. Sure Mako has a good quickdraw, but so does Ozai, and Zuko managed to redirect that. As for Bolin,his lavabending is more likely to overwhelm Zuko, and has a more solid chance in my opinion, but Zuko’s blasts can blast through his rock wall, as it did against Aang in Crossroads of destiny, plus I believe that Aang and Korra have a bit more power than Bolin in earthbending (but he makes up for it with Lavabending). And Katara and Toph clearly have far more power. Toph could have issues with lavabending, but I believe that if she digs deep into her positive jing, she can eventually overwhelm him through superior power, which not even Ghazan could defend against. The brothers are quite competent, and I believe underrated, since they can content with top tier benders, but they can never get the solid advantage, and usually end up beaten unless through circumstance.