There are only 17 Grass-type Pokémons in Ruby version.
Water-type Pokemon are weak against Grass and Electric-type moves.
Torchic (fire-type), Mudkip (water-type) and Treecko (grass-type)
a very strong grass type Pokemon who knows good grass type moves, and a rock type Pokemon that knows rock type moves. hope that helps!
A Geodude and a Nosepass. You should be fine with a fighting type, a water type, or a grass type.
gloom and nuzleaf to shifery
In Pokémon Ruby (and Sapphire/Emerald) the three starters are Treeko (Grass type), Torchic (Fire type) and Mudkip (Water type).
Catterpie, Roselia, Scyther and many many more grass type Pokemon can learn bug type moves.
a swampert, lombre, or sceptile. if you don't have one then use a water or grass type
Type Pokemon Ruby and then type CCG.
The first fighting pokemon you can encounter in Ruby is in the cave at the island with the second gym. That one is makuhita. You can also catch a Shroomish in the forest south of Rustboro. Shroomish evolves into Breloom who is a grass/fighting type.
Wattson is easy as long as you have a ground type Pokemon like Marshtomp and use ground type moves like mud shot or have a grass type Pokemon like Grovyle or Breloom.
There are no grass type Pokemon underground!