He makes a lot of mistakes in the ring but pulls it out because of his determination
He doesn't make many incompetence mistakes in the ring. The mistakes he does are mostly the kind every other boxer in the anime makes as well.
To my knowledge so far he has only made... exactly 2 real mistakes in a match.
So yeah, his biggest advantage is his strength, and it's totally justified.
His major strengths are
1) Strong punches
2) Fast dashing
3) Super fast learning curve (he is the ONLY character that could learn a move specifically to counter his opponent and master it in time... some during the same fight... or instantly)
4) Great pain tolerance
5) Cerebral buffer (I don't know the correct term for this... he seems to recover from brain injuries quickly)
6) Amazing Eye Acuity (They never state this, but it becomes obvious early on)
7) Supreme Stamina (Which... either exists or doesn't exist depending on the episode...)
They USUALLY don't paint him as a moron, I exaggerated. But a few fights really don't seem to realize that our hero is fantastic. He certainly has more of a collection of advantages then any of his opponents who would stand no chance if Ippo had more experience.
Which is really the thing the only true disadvantage Ippo has, other then ones they make up for drama, is experience.
He's strong because of his helping with his mother's business ever since his dad died.
To a certain extent this is true. But you need to be more then strong to translate into those strong punches he does. Most people have to actually train to throw proper punches... he got it after someone just explained it to him once.
He isn't "stronger then the other opponents" he punches harder then they all do.
In his defense Ippo is seriously Stout... All his opponents have a serious height advantage on Ippo and yet are the exact same weight. So Ippo's weight all comes from muscle. To a certain extent it kind of makes me wonder why his muscles don't show more... but I take it as artistic license.
They don't paint him as a moron, he just has a meek personality because of his growing up being bullied..
Hey, I said that earlier. As well early in the series they certainly paint him as a genius.
Heck one fight in particular removes an ability Ippo used earlier, as I stated earlier, and he had to relearn it (canon discontinuity... as it retroactively removed that ability...)