The Team in general
I don't see Mega-Venusaur nowhere. Mega-Venusaur is like a staple slashable anywhere in Mono-Grass because of its ability Thick Fat that allows it to take Fire- and Ice-type attacks for mono-Grass like no other tomorrow will. Pair the froggy botanical dino-mons.. okay I'll stop.
Pair Venusaur with Ferrothorn for assured success; Ferrothorn utterly cancels Poison-, Psychic- and Flying-type weakness for the team while Venusaur reciprocates by dealing with pesky Fire-types that beat Ferrothorn anytime.
So far, let's drop Mega-Sceptile and its meager albeit somewhat useful niche in Mono-grass (beating dragon when correctly played) and replace it with Mega-Venusaur.
Then. As you will want to keep offensive presence on the field, Shaymin-Sky will do wonders. This dude is allowed on Mono-Grass and is a godsend for the type wholly, from its blazing speed and special attack to Serene Grace Air Slash. It will be a good replacement for Rotom-Mow which isn't very useful in Mono-Grass, lacking synergy to contribute to the good of the team.
So Venusaur > Sceptile and Shaymin > Rotom-Mow.
Set fixes:
First off, never ever ever do the the 252 Def / 252 SpD in EVs. This renders your Pokemon mediocre on trying to be good at everything. Cradily will want to use its 107 base Special Defense to great ends. For this, a spread of 252 HP / 252 SpD / 4 Atk will maximise the special bulk of this plant along with a Sassy Nature. Then, Rock Slide's superior power and PP will make you want to leave useless Ancient Power and its meager PP and damage output alone. Then, Recover is better than Giga Drain as you have a team of 6 to use Grass-type attacks whereas Recover grants instant sustain that's more reliable to a hazardous damage output move. Finally, Toxic will cripple enemies much harder than Confuse Ray will.
The set:
Cradily @ Leftovers
Ability: Storm Drain
EVs: 252 HP / 4 SpA / 252 SpD
Careful Nature
- Stealth Rock
- Giga Drain
- Rock Slide
- Recover
Should be good enough at stalling and covering your team's weakness.
Venusaur @ Venusaurite
Ability: Chlorophyll
EVs: 232 HP / 252 SpA / 4 SpD / 20 Spe
Modest Nature
- Giga Drain
- Sludge Bomb
- Hidden Power Fire
- Synthesis
You're pretty smart so you should understand how this dude works. It's an all out offensive beast because Cradily and Ferrothorn are already good enough at defense together. It has dual STAB and Hidden Power for coverage. Synthesis allows it to sustain. EVs maximize the power of whatever monster Venusaur is based on, with some speed allowing it to outspeed Adamant Azumarill while factoring IVs necessary to be run with Hidden Power Fire. Rest is dropped into bulk but 4 EVs go to special defense to give odd number of HP, minimizing hazards' damage.
Shaymin-Sky @ Life Orb
Ability: Serene Grace
EVs: 252 SpA / 4 SpD / 252 Spe
Timid Nature
- Seed Flare
- Air Slash
- Earth Power / Hidden Power Rock
- Healing Wish
All out attacker; dual STAB for their power and desirable second effect Serene Grace contribute to boost, with Earth Power swappable for Hidden Power Rock if desired. Healing Wish allows self-sacrifice and a more reckless playing for at death moment, it insta-kill Shaymin to breath life to the nextcomer.
Sempiternus has it alright. I won't restate what he said, but rain cleaner is the mexican pineapple's only viable set. In mono-Grass at least.
Ludicolo @ Life Orb
Ability: Swift Swim
EVs: 4 Def / 252 SpA / 252 Spe
Timid Nature
- Hydro Pump
- Giga Drain
- Ice Beam
- Rain Dance
There you have it.
Breloom @ Focus Sash
Ability: Technician
EVs: 252 Atk / 252 Speed
Jolly Nature
- Spore
- Bullet Seed
- Rock Tomb
- Mach Punch
Spore puts to sleep your foes; you get the opportunity to beat enemies with your strongest STAB Bullet Seed, speed control and common coverage in Rock Tomb and Mach Punch as priority and good STAB too. If you feel like it, though, Swords Dance can be used instead of Rock Tomb for more power VS coverage.
Ferrothorn @ Leftovers
Ability: Iron Barbs
EVs: 252 HP / 88 Def / 168 SpD
Relaxed Nature
- Spikes
- Leech Seed
- Gyro Ball
- Power Whip
EVs allow you to fare well against both physical and special attackers alike. Has hazards Control along with Cradily with Spikes and Stealth Rock. Leech Seed to life and dual STAB that put bad speed to use.
I hope this helps!
