I love Mudkip cuz of the 1 weakness to grass thing. I got mudkip as my starter and bulbasaur as my partner. I know probably should have gotten a fire type to keep those grass types off but i just love bulbasaur. Id suggest bulbasaur or charmander as your partner.
Charmander perks: -Fire is good to kill grass with (swamperts 1 weakness)
-Charizards eventual electric weakness is smothered with swamperts ground typing
Bulbasaur perks: -Also can use poison moves to kill grass with (swamperts 1 weakness)
-Immune to leech seed (good for grass countering)
-Mudslap Leechseed combo in the beginning really kicks ***!
Anyway, just restarted my game and felt i should throw in my two cents