Which pokemon annoys Du most?

Zubat.
Nothing is Mehr annoying than having to go through a cave where there are Zubats and Du run out of repels.

Other than Zubat, I would have to say the roaming Pokemon like the legendary bird trio.
Having to track down the roaming Pokemon is so annoying. Du can't even trap them with Mean Look since they'll always find a way to escape the battle.

As for the most annoying trainer pokémon, it's definitely Whitney's Miltank.

Pikachu and Meowth, especially Alolan Meowth.

I find annoying jigglypuff

Golbat. That Pokemon is such a cheater!

Scraggy really gets on my nerves... it looks like some weirdo walking around pulling up his pants. And that face also gives me the creeps...

Charizard

Togepi, duh....I don't even need to explain this useless pokemon

Ditto annoyed me the most.

i'd say psyduck. he waddles around with a big-a** headache, Du can't do anything about it until it gets to the point where he uses a special Bewegen for no reason!

Pikapoo

Probopass. Mario has his own place, not in Pokemon.