Best Pokemon Team for a Water Gym?

Before you read: Pixelmon is JUST like pokemon. The reason that I'm noting it is because of the huge restrictions that are put on you when battling to make it harder

Let me explain my situation. Pixelmon is just like Pokemon in Minecraft. I'm trying to beat the first gym, but it is really hard, as there's a level cap of 25, it must be a 3 vs 3 team, and the gym leader has Marshtomp, Lapras, and Starmie, all at maximum levels. Only like 20 people out of the entire server have beaten any of the water gym leaders, and I have already tried twice. Also, there's a $250 in-game currency fee per attempt (kind of a lot in game) and the line takes about 2 hours. Also, you can't enter the line 2 hours or less before your last attempt, so there's kind of a thing discouraging re-attempting.

I'm trying to find the best Pokemon for the job, and it is not working great. I've tried a Gyarados, Pignite, and Swadloon team (all level 25) and a Swadloon, Servine, and Fearow team (also level 25 apiece). I'm replacing the Fearow with a Voltorb. However, what do you think I should try? Remember that he has Marshtomp, Lapras, and Starmie.

PS. A little side note on the rules to make it even harder:
1) No healing is allowed whatsoever during battle (not even attacks like Absorb or Mega Drain)
2) Moves that give your opponent status ailments 100% of the time when hit are not allowed (Sleeping Powder is not allowed but Poison sting is, as poison sting does not poison 100% of the time)
3) Moves that inflict a very specific amount of hp damage are not allowed (Dragon Rage)
4) Protection and the likes are not allowed
5) K.O. Moves are not allowed
6) Disabling moves are not allowed
7) Pokemon may not hold items during battle
8) Your pokemon may not be above lvl 25 (Leveling is disabled durning matches, you your pokemon will not level up or gain experience during the match)

Good luck with that one. Thanks in advance

Added (1). Also, no legendaries

Added (2). I'm not exactly an adult (or even close to it)

Get a life

Lapras and Starmite are both pure water pokemon so therefore you'll want to get a pokemon that is an electric type or a grass type. These both are super effective against the water types. Marshtomp is a ground/water type pokemon, so therefore electric types are ineffective against it. A grass type however will still be effective since they are super effective on both water AND ground types. Now the pokemon I would choose (however I'll warn you, I don't know too much about the pixelmon mod so I don't know if they have the pokemon I'm gonna list) are Voltorb, Pikachu, Grottle (or a Turtwig will suffice lol). Also here's a chart that may help you when fighting other gym leaders: http://pokemondb.net/type (you'll need to scroll down a little)

Definitely wanna go with 2 grass if they're strong in that game. An Ivysaur with strong Razor Leaf or Vine Whip would be good.

2 grass + 1 electric. Probably your best bet, don't let the electric type go up against marshtomp though.

What pixelmon server do you play on? Would love it if you could come chat at my website about it. Link is below