Comparatively weak, not outright weak - Scraggy is probably the best example of development on Ash's team in terms of being reasonable increments in power.
The problem I'm pointing to is that Scraggy and Axew started out at the same level, Axew had Scratch and Scraggy had Headbutt - and they both did about the same damage to eachother. They then did the majority of their training together, Axew all of a sudden got one of the most powerful Dragon type moves in Dragon Rage and then Axew was suddenly way ahead in power. Then before Scraggy gets a chance to catch up, Axew gets Outrage as well. After finally getting Hi-Jump Kick to even vaguely have a poweful attack, just as Scraggy starts to build up strength and gets Focus Blast - all of a sudden Axew gets Giga Impact to just knock back any progress Scraggy might have been making in getting close in strength again.
Iris doesn't put in any more training than Ash - yet Axew's results are far superior. Axew was 'recently hatched' when given to Iris and was certainly at the same power level as Scraggy in their first battle, so I don't buy being younger as an excuse for it. Scraggy's weakness is that he gets trained just as much, by someone just as skilled if not moreso as a trainer, but the results are no where near equal - which makes Scraggy look weak in comparison to Axew.
Scraggy's storyline is good - I certainly don't want Scraggy to have instead mastered Focus Blast instantly or got another massively powerful move to bring it up to par - I just want Axew to have developed at a similar rate and not keep constantly being a massive leap ahead of a Pokemon it started out as being on the same level of for no good reason.