Venusaur is extremely slow, and given the huge disadvantage in duels for any type, including water types, I would suggest a speed boost, or a leech seed, which is one of her main moves.
I have some suggestions to improve shiftry, his typing is the worst in the game, so he needs a set with more counters.
P Worry Seed
P Razor Wind
m1 Faint Attack
M2 Grassy Glide --- Bounce
m3 Razor Leaf
m4 Natural Gift
m5 Foul Play
M6 Night Shade----Fling
m7 Grass Knot ---- Rock Tomb
m8...
I think it’s hard to increase his speed, he’s a naturally slow pokemon, you can improve his set moves, with seed bomb, bullet seed, some move water he learn on bulbapedia