Level 16
It would be hard to beat him without evolving it in to swampert first, because then swampert can learn muddy water. But marshtomp's most effective move should be Mud shot.
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.
Level 1- Tackle, Defense Curl Level 6- Mud Sport Level 11- Rock Throw Level 16- Magnitude Level 21- Self-destruct Level 26- Rollout Level 31- Rock Blast Level 36- Earthquake Level 41- Explosion Level 46- Double Edge
Krookodile learns Bite at Level 4, Sand Attack at Level 7, Torment at Level 10, Sand Tomb at Level 13, Assurance at Level 16, Mud-slap at Level 19, Embargo at Level 22, Swagger at Level 25, Crunch at Level 28, Dig at Level 32, Scary Face at Level 36, Foul Play at Level 42, Sandstorm at Level 48, Earthquake at Level 54 and Outrage at Level 60.
Level 16
Marshtomp learns Mud Shot at level 16.
marshtomp learns good moves in level 16 he learns mud shot but u have to train so it could learn good moves or just maake him learn moves by tm.
It would be hard to beat him without evolving it in to swampert first, because then swampert can learn muddy water. But marshtomp's most effective move should be Mud shot.
Keep using Marshtomp's Mud Shot, it will lower their speed, and then you should use Water Gun.
Mudkip evolves into Marshtomp at level 16.
She has a Level 19 Marshtomp that only knows Mud Slap.
This move set is applied to Pokemon Ruby, Sapphire, Emerald, FireRed, and LeafGreen and changes could have been made to the future games. Marshtomp can learn Tackle, Growl, Mud-Slap, Water Gun, Bide (Level 15; before Mudkip evolved), Mud Shot (Level 16), Foresight (Level 20), Mud Sport (Level 25), Take Down (Level 31), Muddy Water (Level 37), Protect (Level 42), Earthquake (Level 46), and Endeavor. (Level 53) It can learn these TMs and HMs as well: Water Pulse, Toxic, Hail, Hidden Power, Ice Beam, Blizzard, Protect, Rain Dance, Frustration, Iron Tail, Earthquake, Return, Dig, Double Team, Rock Tomb, Facade, Secret Power, Rest, Attract, Surf, Strength, Rock Smash, Waterfall, and Dive. These are its Tutor Attacks: Mega Punch, Mega Kick, Body Slam, Double-Edge, Counter, Seismic Toss, Mimic, Rock Slide, and Substitute.
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.
Krabby can learn: Leer (level 5), Vicegrip (level 12), Harden (level 16), Mud Shot (level 23), Stomp (level 27), Guillotine (level 34), Protect (level 38), Crabhammer (level 45), and Flail (level 49). If you go to a tutor it can learn: Swords Dance, Body Slam, Double-edge, Mimic and Substitute. There are also 18 TMs and 5 HMs that you can teach it.
Best bet is to get a high level ground type with a good ground type attack. I found it easy if I chose mudkip as my starter because by then it should have evolved into marshtomp. Marshstomp is part ground type so it is immune to electric attacks, and it should know mud shot or something to take down his pokemon.
In Pokémon Emerald, Marshtomp will know moves such as Mud-slap, Growl, Tackle, Bide, Water Gun, Mud Shot, Mud Sport, Foresight, Muddy Water, Take Down, Protect, Earthquake, Endeavor, Hail, Water Pulse, Toxic, Ice Beam, Blizzard, Return, Frustration, Hidden Power, Rain Dance, Iron Tail, Earthquake, Dig, Double Team, Facade, Rock Tomb, Secret Power, Attract, Rest, Strength, Rock Smash, Waterfall, Surf and Dive.