Use Surf on Route 205 and you'll easily find a Tentacool.
I don't know where you can find a trainer with Tentacool, but you can easily find it surfing on Route 205.
you can get one in pastoria city.Use surf and there is 75% that tentacool will come.
everywhere on water
Tentacool can be found in the water all around the route's near sootopolis city, mossdeep city and pacifidlog town.
you can find it by fishing or just surfing on the water..........
it is Tentacruel
Around the beach in sandgem town you don't need to fish you need to surf intil tentacool appear
if you have surf then anywhere with water
Tentacool evolves into Tentacruel at level 30.
Tentacool evolves into Tentacruel at Level 30.
You can get it from a trade, the GTS, or find it possibly in the waters between the Fight Area, the Resort Area, and the Rest Area. You can find tentacool by just surfing just about anywhere. Or, using a good rod or old rod.