If I may, You gotta had an Aggron and Scizor. Your choice of Forretress and Mawhile, but you already got a physical wall so I would be leaning towards Mawhile.
Anyways I started my Water monotype challenge with my projeted team being
Blastoise
Seadra
Slowbro
Powliwrath
Lapras
Vaporeon/Kabutops/ if someone makes a suggestion ( please)
So I headed of on my journey to complete another monotype challenge. Fun fact my poison challenge was the first time I went thorugh the game without a starter. Anyways I obviously picked Squirtle for my starter and I named him pools

. After thinking to myself 1000 times that it's going to be hard seing as I wont get another water type poke till after the 3rd gym ( unless I wanted to use the Magikarp) I went into viridian forest rushing to brock and defeating him in a second. Pools evolved to Wartortle and I went to mount moon, being so high leveled I demolished anyone and everyone and did the same in mount moon. I got to cerulian and went to challenge my Rival. I somehow died to him and then rematched him to beat him.
After doing to little in-game stuff I went on to beat Misty which as lead me to make it to Vermillion city. I have had much debates about whether I should say Lt Surge for a Slowpoke or something or just go right ahead and defeat him with Pools. Either way it will be challenging.
Team is as followed
Pools the Wartortle = 30