Depends on the character, sorry but it's the only true answer here. Some characters slide too far to do anything, others have moves that are too short, etc etc... Some characters will hit you or grab you because they have the range, an item in hand, or the traction to prevent them from sliding too far. Also, it depends on the terrain where you're at, if you hit them with your aerial hammer next to a slope that goes upwards, chances are you're safe. If it's a slope that goes downwards, chances are you'll get hit.
I figured that I should have asked if aerial hammer is safe in general, but you do bring up a lot of good points, I, however, was not under the impression that aerial hammer could be shield grabbed b/c it was disjointed. Unless the shield stun on that move is garbage which I do not believe is true either.
In regards to inhale as a mixup: Don't bother. The risk/reward has too great a risk. If you see any top Kirby videos, you'll notice they never inhale.
It's true that the risk/reward is not that great for Inhale, especially when you factor Kirby's weight which isn't the worst but isn't like DK/Snake where you can keep going for ridiculous options because you have the % to tank it. However, the problem I see is that bair can get ridiculously stale to the point that people with decent OoS games can punish it even without perfect shielding it. It just seems to me that going against opponents who are shield happy once they see you in the air, b/c they expect that bair and they know they can punish, would be very susceptible to essentially an air grab.
Good players don't use Inhale
Inhale
would be a good mix-up against a Shield except that it doesn't hit until at least frame 19. This gives both good players and not-so-good players the chance to punish you. The good players will usually react in those 18 frames and either dodge or hit you before the Inhale lands. The not-so-good players will not consciously understand the situation but they can have a 'knee-jerk reaction' to your approach and hit you anyway (jump-canceled Shield into Aerial or U-special being the most common).
There's always the chance that the opponent is simply bracing themselves for the ShieldHitLag that they expect. This is where they have a routine response to someone hitting their Shield and then executing a specific attack. Someone sitting in their Shield like this can 'freeze up' when they see the Inhale start; they've told themselves to hold that Shield no matter what. In this instance the Inhale will succeed as a mix-up. The bummer is that for all this work the reward is pretty paltry.
First off, great post addressed a lot of things that I found helpful. The issue with opponents that have an automatic OoS option which will beat inhale is very valid. But few characters imo have a good automatic OoS option like Marth's fair that would be safe to just throw out there. Which is why barring a few MU's, it could still be a decent mixup.
The issue of the reward being rather meh has been mentioned quite a few times though, but isn't this the same with D3? As in couldn't we also apply inhale similarly to how D3 does inhale? Granted I understand that there a couple of key issues that prevent Kirby from totally applying inhale like D3, mainly the fact that he isn't as heavy so he must be more stingy with the damage he takes and that he doesn't fall nearly as fast so it won't catch people off guard as easily either (it also seems that D3's inhale comes out a bit faster(?) but there is not frame data for him on his inhale), but when Kirby is hovering in the air or SH'ing with his back toward you, as the opponent you know that bair is going to come out almost 100% of the time. This is also the same situation with D3. Yet D3 (well maybe just Coney) use Inhale very successfully as a mixup, and I don't see why Kirby should not incorporate it more into his game.
Also imo the risk/reward is actually not as bad as people put it in the situation I am thinking about: When your bair is already stale because your past 3-5 hits have been with it and you still want to keep up some pressure. Let's consider the case that your opponent's character can start punishing your bair once it has staled 4-5x because of its reduced shield stun. In this case, the reward of using bair and not getting punished is 1) some more shield decay or 2) damage of a decayed bair. The risk would be the % dealt by their best punishment option. If you use inhale instead your reward would be 1) Damage from a fresh move 2) Situational (MU Dependent) option of Kirbyciding 3) Reduce Decay on bair 4) Keep opponent wary. The risk would be the same, because, as Timmy pointed out, the only thing that would stop a mixup inhale preemptively would be their automatic OoS option.
Thus the % spread for stale bair and its potential followups and the damage you would take for getting punished vs the damage you get from fresh inhale and the damage you would take for getting punished is pretty similar and inhale accomplishes a bit more for you. I feel that some of you are under the impression that using inhale will lead into a very high % punish from the opponent which it could but I feel that's overgeneralizing. If you conditioned your opponent to expect that bair (something that most Kirby's probably end up doing intentionally or unintentionally), then the punish the opponent has would be their knee jerk OoS reaction to seeing inhale which shouldn't be any different from how they would plan to punish your bair granted that they could punish your bair in the first place.
Well sorry for the wall of text, I hope you don't pass this off as mindless theorycrafting, because I do believe that I have some practical legitimacy in my thoughts.
