How do Logia powers work?


PS: Warning, not sure whether parts should be considered spoiler.

It is said that Logia typed Devil Fruit Users cannot be hit without Haki. Yet
while re-watching the Alabasta Arc, Ace was touched twice by Luffy. The first
time when he flew inside the restaurant, Luffy hit Smoker and threw him up
against Ace, both making a huge hole in the next couple of buildings. The
second time was when Luffy was arm wrestling Ace, although this scene might
not be canon though. So my question is, how was Luffy able to push back both
Smoker and Ace when flying inside the restaurant, since he shouldn't be able
to. Does this mean Logia users can "solidify" themselves or maybe only parts
of themselves, kind of like coating with Haki? Also what would be the default
form for a Logia user?




> It is said that Logia typed Devil Fruit Users cannot be hit without Haki.

Luffy using water to hit Crocodile shows that Logia typed Devil Fruit's
weakness can be used to hit without using Haki. So to harm a Logia is to
exploit the element itself, using its properties to solidify the user and
rendering them vulnerable to damage.

[Source](http://onepiece.wikia.com/wiki/Logia#Weaknesses)

> Despite the fearsome power of Logia users, they are far from truly being
> invincible. Sneak attacks are more likely to work, as the user will not be
> ready to avoid them. However, with training, most Logia users learn to
> transform by reflex, eliminating the ability to strike them by conventional
> means. For example, Enel's ability has been trained to the point that he
> could reflexively change form while partially asleep using Mantra to predict
> his enemy's actions.
>
> Inexperienced Logia users also tend to become seemingly overconfident, as
> they are unaccustomed to physically dodging attacks or receiving attacks,
> due to their powers. Thus, if their advantage is neutralized by some means,
> they then have to rely on their physical ability to dodge, a skill which
> they may or may not be proficient at.

Very high skill and training required to dodge any sudden attack. Physical
contact is required to hit Logia user, so a well trained user can avoid Haki-
imbued attacks by changing the state.

> Does this mean Logia users can "solidify" themselves or maybe only parts of
> themselves, kind of like coating with Haki?

Yes they can solidify and turn there part of body as they want. Crocodile hand
turn into sand while he was holding Vivi. Aokiji using ice leg in One Piece
Film: Z.

So it is clear that default form is human state and change according to
requirement. And can be hit without using Haki.

