How to Get a Mudkip in "Pokemon FireRed"by Darren Bonaparte ; Updated September 22, 2017
Items you will need
Two Nintendo DS systems
"Pokemon FireRed" is a reboot of a first-generation Pokemon games with improved graphic and different designs. Just like the original game, you may choose between the starters (first Pokemon) Bulbasaur, Squirtle, and Charmander. Unfortunately, the water-type Pokemon, Mudkip, of "Pokemon Emerald," isn't available as a starter or through any events during game-play. This doesn't mean that a Mudkip isn't available; it simply takes a bit more work.
Finish the first section of "Pokemon Emerald" by beating the Elite Four once. After this you are allowed to visit the extension areas, the Sevii Islands. There is a machine on Island One that allows you to trade with other games. Through normal game-play, you will fix the machine. At this point, trade is possible.
Save the game and turn the system off. Boot up the second DS system containing "Pokemon FireRed."
Head to a Pokemon Center in any town except Pallet Town and head to the left. Upstairs there will be a desk where a worker will ask if you wish to trade. Select "Yes."
Turn the other DS system ("Pokemon Emerald") on and head to a Pokemon Center. Talk to the trading desk as well and select to trade. Select Mudkip (or Swampert if evolved) in "Pokemon Emerald" DS to trade Swampert.
Have the "FireRed" system trade a Pokemon in return.
Get Mudkip by putting Swampert and an opposite gendered water-type Pokemon in the Day Care Center. If the man outside the Day Care Center says they are getting along well, walk around a bit and you will come back to an egg.
Ride your bike for an extended period with the Swampert egg in your party as one of the six slots. Once it hatches, if all goes according to plan, you will be the proud owner of a Mudkip.
An Action Replay system and cheat codes can also be used to obtain a Mudkip, but this can damage your system and is considered unsafe.