TLDR: Against Slowbro, use:
- Parasect with Solar Beam
- Exeggutor with Solar Beam (but swap in Raichu if you see Ice Beam)
Slowbro is a surprisingly good defender. It has decent base stats, and high enough CP to put in a gym.
But Slowbro really shines when it comes to type defense.
Grass is your best counter to Water/Psychic:
- There’s no Dark in this meta, so Dark moves lack STAB
- Ghost (Gengar) has Poison as a second type, making it vulnerable to Psychic
Most Grass types are ruined by having Poison as a second type. This leaves you with:
Slowbro has a defensive Ice move set. While it’s not Slowbro’s strongest move, it does neutralize the biggest threat: Exeggutor. If you see Ice Beam, you would swap out your Exeggutor with Raichu.
With Exeggutor being situational, Slowbro’s only real counters are whittled down to lower tier Grass types: