Hi there Sea34! I remember back when I was trying to learn the ropes of competitive battling, it's a lot of fun once you get into it! Hopefully I am able to help you out.
Now first off, is this team for Doubles or Singles use? If this is primarily Singles, I suggest removing Surf on your Pokémon and giving them Scald, a really good option since it can burn the opponent. I'd like to suggest Hurricane over Roost on Pelipper, it's 100% accurate in the rain and it's a powerful STAB move with a chance to confuse the opponent. Great choice in Kingdra, but Scald over Surf is the best way to go. Toxicroak is an interesting Pokémon but it's not cut out to be a mixed attacker, so put Knock Off and Drain Punch on there over the Special Attacks. Mega Gardevoir is great, but not for Wish sadly, if you still want a Wish-mon, I suggest Vaporeon. However instead of Wish and Rain Dance, how about Thunderbolt and Psyshock? Also I would use Moonblast over Dazzling Gleam. If you want to play a tricky Gardy set, and don't mind losing her Mega, I've been using a Z-Magic Room set. Z-Magic Room boosts your Special Defense by 1 and makes held items lose effect for 5 turns, but because of this don't lead with her or Pelipper's Damp Rock won't work. Goodra is one of my favorite Pokémon! Good set IMO, but maybe scrap Rain Dance for Sludge Wave, I'm sorry I have never used Goodra in competitive battling. Heliolisk!!! I'm using one on a Sunny team lol! Volt Switch and Focus Blast can stay, that's good, but put Dragon Pulse and Hyper Voice on, Hyper Voice is amazing as it's a STAB move for Heliolisk.
I hope I was able to help you out with this team, good luck and let me know how you do!
Also if you require further assistance with team building, feel free to PM me, or another user I can recommend is @RetroTyphlosion
Now first off, is this team for Doubles or Singles use? If this is primarily Singles, I suggest removing Surf on your Pokémon and giving them Scald, a really good option since it can burn the opponent. I'd like to suggest Hurricane over Roost on Pelipper, it's 100% accurate in the rain and it's a powerful STAB move with a chance to confuse the opponent. Great choice in Kingdra, but Scald over Surf is the best way to go. Toxicroak is an interesting Pokémon but it's not cut out to be a mixed attacker, so put Knock Off and Drain Punch on there over the Special Attacks. Mega Gardevoir is great, but not for Wish sadly, if you still want a Wish-mon, I suggest Vaporeon. However instead of Wish and Rain Dance, how about Thunderbolt and Psyshock? Also I would use Moonblast over Dazzling Gleam. If you want to play a tricky Gardy set, and don't mind losing her Mega, I've been using a Z-Magic Room set. Z-Magic Room boosts your Special Defense by 1 and makes held items lose effect for 5 turns, but because of this don't lead with her or Pelipper's Damp Rock won't work. Goodra is one of my favorite Pokémon! Good set IMO, but maybe scrap Rain Dance for Sludge Wave, I'm sorry I have never used Goodra in competitive battling. Heliolisk!!! I'm using one on a Sunny team lol! Volt Switch and Focus Blast can stay, that's good, but put Dragon Pulse and Hyper Voice on, Hyper Voice is amazing as it's a STAB move for Heliolisk.
I hope I was able to help you out with this team, good luck and let me know how you do!
Also if you require further assistance with team building, feel free to PM me, or another user I can recommend is @RetroTyphlosion
OU MASTER RACE