Here is one:
Modest Nature(+Sp Attack -Attack)
- Hyper Voice
- Shadow Ball
This is a standard sweeping set for Sentret. I noticed that Sentret has higher Attack but it has a wide Special Movepool and it cant be a Physical Sweeper, as It gets outclassed. Hyper Voice is STAB for Sentret that Is actually good. Flamethrower is for those Steel types you might face. Shadow Ball to really damage Ghost types like Gastly. Trick is to switch Items with the opponent, pretty gimmicky if you ask me.