I actually posted something about the "toxic" issue on another thread...Let's see where it was...
The Komodo Dragon are well known for their bites since they have many different types of disease carrying microbes in their mouths that when they bite you, if you don't get some sort of shot right away, you could lose the limb just for that.
Then for the inanimate, you have bacteria that settles on dirty surfaces, when handled improperly you can make yourself sick.
I think that's why Toxic is a Universal TM.
There is only one other move that I can think of that can inflict Badly Poisoned and its strictly to Poisonous Pokemon.
Humans are similar with Blood types and donors. Others may not accept the organs or blood safely even being matching types. Auto-immune disease in cases like these aren't as common, but possible.
Then you have genetic illness carriers who are immune to the disease themselves, but still carry the gene that carries it.
As for Komodo, they can easily be anything else if the creators want it to be. I can see on as Pure Dragon based on name, Dark due to way they hunt and because of how they are mentally, they could be Water or Grass due to habitat.
Its based on what the creator would want for it.
Most common WOULD be poison. XD Even I made a Poison/Dragon Komodo Fakemon.
Pokemon learning Poison attacks is actually the easiest to explain with those two above.
For others, its affinity. When you think of basic Monsters from RPG there are some that have better affinities than others. In Pokemon's Case Normal types usually have the best affinity and learn a multitude of type attacks to make up for their neutral disposition.
Some moves you have to look past their Anime version or localized/translated namesake. In terms of Aerial Ace or Swallow Return, is based off a Japanese Sword style where they user attacks at a high speed and returns the blade back to its original position quickly. The attack was developed after watchin a Swallow hunt which is where it got its name. The Anime version sorta bastardizes the attack into a high flying never miss attack, but all it is is a quick hit and run attack that's hard to dodge. Even a Diglett could do it by popping underground and attacking the unaware opponent.
Its hard to give it form against a Pokemon with Levitate or one always shown flying, but if you are creative enough it can make sense once you push past what is normally shown since a lot of Pokemon use attacks differently or attacks have changed over the 15 years of Pokemon.
When you are as open with your thoughts like that, no...none of the attacks seem out of place in anyone's move pools at all.
My friend always questioned how a Trapinch was capable of using gust when they are depicted as wingless insects. I usually made the joke that Trapinch had a really powerful burp. XD
Anything can be possible with Pokemon sometimes you can look at it logically sometimes you cannot and have to go the magic route and just accept it.