Where and how do you get the marsh badge?

Beat Sabrina in Saffron City Gym to get the Marsh Badge. You can only enter the gym after defeating Giovanni in the Silph Co. Building. To get in Viridian Gym, you must obtain all 7 previous badges.

You have to beat the Gym leader in Saffron City. But you have to beat Giovanni in the Silph Co. Building before you get to go in the gym. You do need it to get into the Viridian Gym.

You beat the gym Leader, you also need to save silph.co first before you can gain acces to the gym.

Here's a good treat for you-after you beat Giovanni in the gym, go to the spot exactly where he was standing before he takes off, use your itemfinder on exactly that spot-and you will get a nice surprise! There are other items like this in the game-ask another question if you'd like to know more! I'll find it hopefully in a short time and you'll have some cool stuff if you bother to ask, but you can find me around if need be. Enjoy it!
BBG_CREECAT

In order to gain access to the Saffron City Gym you need to go through the Silph Co. Building. While inside you will encounter many Team Rocket Grunts or Pokemaniacs. After you get the card key unlock the door to left on floor three. If you wish, you can battle the pokemaniac, but I recommend not battling him because before you can battle Giovanni, you have to battle your Rival. I recommend getting as many revives and hyper potions as you can because your rival is hard to beat at this point. He will probably have a level 37 Pigeot, a lv. 38 exeggcute, a lv. 40 Charizard, Blastoise, or Venusaur, (depending on which Starter you have) a lv. 35 Alakazam, and a lv. 35 Gyarados. If you Have Pokemon over lv. 60 then you'll probably beat him pretty easily. I would get fire Pokemon, eletric Pokemon, and grass pokmon and if your rival has Charizard then I would get a water Pokemon, too. After you beat your rival you battle Giovani. I would save your game before and after you fight Giovani and your rival so that way if your game freezes or you lose you can start where you saved. Right before you get to Giovani you Have to battle a Team Rocket Grunt. The Grunt has a lv. 32 Cubone, a lv. 32 Drowzee, and a lv. 32 Marowak. If some your Pokemon fanited while battling your rival Iwould revive them and them use a potion on them to make sure they won't faint right away and so that you have more then one Pokemon still usable, and if any of your pokemons PP runs out replenish that if you have any ethers or elixirs. If any Pokemon got hurt I would heal those ones, too. After you defeat the Grunt you battle Giovani. He has a lv. 37 Nidorino, a lv. 41 Nidoqueen, a lv. 35 Kangaskhan, and a lv. 37 Rhyhorn. Before you leave talk to the president. He then gives the Master Ball. Then you can leave the building by using an escape rope or go down the using the teleporters and the stairs/elevator. NOTE: After you beat Giovani, everyone there that is from Team Rocket will leave and you don't have to battle anyone for a while. After you beat Giovani you can enter the Saffron City Gym.

Beat Sabrina in Saffron City Gym to get the Marsh Badge. You can only enter the gym after defeating Giovanni in the Silph Co. Building. To get in Viridian Gym, you must obtain all 6 previous badges.

I actually beat Blaine before getting the marshbadge and now the guard won't let me pass what do I do