What was the worst catch you had whether by wasting a lot of pokeballs on it or you not liking the Pokémon in question? For me that's hard to say but I've heard some good rants about this on discord.
Regice, think I spend 200 balls on it in total over a few encounters because I ran out. Thankfully none have been as bad as that one so far.
Back when I was trying to catch Meltan a few years ago, it took so many Poke Balls that I almost named it Slippery because it kept slipping out of the Poke Balls.
Now That I think about it took 8 pokeballs to catch. So probably that but I love swablu so it worked out. CLOUDY GUD
Lapras. The first one I saw ate through all my pokeballs and the next ate half before finally getting caught. I dont even like lapras that muxh and it wasnt shiny