Mega Charizard Y team, please help

[sheba987]

Hello guys!
*I'm sorry in advance if I've posted this in the wrong section*

My names Sheba987, it's nice to meet you!
I've been working on my mega charizard y team (VGC doubles) for a while and I've got the solid first five Pokemon who really work well together. However I can't figure out who the last one should be. Or Gyarados's item. What do you guys think the item should be, and what should the last Pokemon be?
But please, no legendary pokemon suggestions, as I would like to keep this team free from them, thank you!

Rhydon (M) @ Eviolite
Ability: Lightning Rod
Level: 50
Shiny: YES
EVs: 252 HP / 252 Atk / 4 SpD
Adamant Nature
IVs: 31/25/31/31/31/31
- Ice Punch
- Protect
- Drill Run
- Rock Slide

Charizard @ Charizardite Y
Ability: Blaze
Level: 50
EVs: 4 HP / 252 SpA / 252 Spe
Timid Nature
IVs: 31/?/31/31/31/31
- Solar Beam
- Protect
- Air Slash
- Heat Wave

Whimsicott @ Mental Herb
Ability: Prankster
Level: 50
EVs: 252 HP / 4 Def / 252 SpD
Bold Nature
IVs: 31/?/31/31/31/31
- Taunt
- Tailwind
- Moonblast
- Helping Hand

Venusaur @ Black Sludge
Ability: Chlorophyll
Level: 50
EVs: 252 HP / 4 Def / 252 SpA
Modest Nature
IVs: 31/?/31/31/31/31
- Giga Drain
- Sludge Bomb
- Protect
- Sleep Powder

Gyarados
Ability: Intimidate
Level: 50
EVs: 252 HP / 252 Atk / 4 SpD
Adamant Nature
IVs: 31/31/31/?/31/31
- Iron Head
- Waterfall
- Protect
- Crunch

Just a quick run down as to why I have those pokes;

I find that having my Rhydon is a good switch in for my Gyarados and Charizard, because he can absorb the electric attacks which would normally kill them. Normally, I'd switch out the Pokemon, normally my whimsicott, into the Rhydon so charizard/Gyarados can have a free shot off while Rhydon protects them. He is also probably my favourite Pokemon out of this team, so please, don't suggest removing him. Even with his massive weakness to grass.

Venasaur works really well with chlorophyll, being able to out speed and put things to sleep. He is also really bulky, and work well as a switch in for my Rhydon. And seeming he has the poison coverage, he can easily take care of those pesky fairy types.

Whimsicott is amazing, even though she dies if you'd poke her with a tad of poison, she can still set up a tailwind or a helping hand before she goes. She also has taunt to help stop any trick rooms, or status moves. Normally, I switch into Rhydon if she's threatened or if I need her for later, because of the tankiness he offers Rhydon can easily live the shot.

Charizard. Well. It's charizard, one of my favourite Pokemon, and he just ruins with his heat wave, solar beam and air slash. Mind you, wide guard spams do get frustrating. But that's why I have whimsicott with the taunt.

Gyarados is really helpful if the sun runs out, or if I need the intimidate on one of their Pokemon. He's also bulky without the d-dance because he doesn't exactly have the time to set one up, he needs to normally get rid of one of their Pokemon who I know will be threatening the others. I've been considering using the white herb for him, so that the landorus intimidate drop is negated, then the waterfall will OHKO the landorus-IF it doesn't switch out and the sun is gone.

But yeah, that's my team so far!
Also-my apologies that part of the post is in blue, I was using my iPad and couldn't figure out how to make it not be blue.
Any feedback you guys have would be greatly appreciated, thank you so much guys!!