Venusaur in Grass for S rank.
Venusaur @ Venusaurite
Ability: Chlorophyll
EVs: 252 HP / 252 Def / 4 SpD
Relaxed Nature
- Leech Seed
- Synthesis
- Giga Drain
- Earthquake
This pokemon is very strong for grass teams. With thick fat giving it an effective resist to both fire and ice, and its poison typing giving it a resistance to bug and poison, this pokemon is only weak to flying out of the five types super effective against grass. Although it needs to mega evolve before it can tank these hits well, once it has done there isn't much that can bring it down between good defensive stats, reliable recovery and only two weaknesses.
Moreover, its movepool allows it to threaten a number of things, with sleep powder being disliked by offensive teams, earthquake dealing heavy damage to heatran, and knock off being a general nuisance. Leech Seed and Giga Drain allow it to keep going without using up too much of synthesis' 8 pp, and its immunity to toxic also helps it stall. Combined with something like ferrothorn or cradily, it easily forms a core that can stop many of the things that threaten grass as a whole.
I'm kinda late on this but I just joined so...
Anyway, I think there are a couple other sets worthy of mention:
Venusaur-Mega @ Venusaurite
Ability: Thick Fat
Shiny: Yes
EVs: 252 Def / 160 SpA / 96 SpD
Modest Nature
- Synthesis/Leech Seed
- Giga Drain
- Sludge Bomb
- Hidden Power [Fire]/Earthquake
This is the standard attacking set for Mega Venusaur. Synthesis is for more immediate recovery, Leech Seed is for making them lose health every turn as well as you recovering health (synthesis is usually better because it gives more recovery and leech seed doesn't work on grass types, sap sipper pokemon, pokemon behind subs, and it goes away if they spin/switch out). Giga Drain is STAB and more recovery, Sludge Wave is secondary STAB. HP Fire hits steel types hard, but leaves you walled by chandelure/heatran/dragalge. EQ also hits steels, but leaves you walled by Skarmory. Make sure to put some EVs in Attack (4-20 is probably good) from SpD or Def if you choose EQ. You can also run 92 speed to outrun 252+ speed base 50s (aggron/mega aggron/mega mawile/azumarill/chansey [please don't run 252+ Spe chansey...] etc.)
Venusaur-Mega @ Venusaurite
Ability: Thick Fat
Shiny: Yes
EVs: 4 HP / 232 Def / 20 SpA / 160 SpD / 92 Spe
Bold Nature
IVs: 0 Atk
- Synthesis
- Leech Seed
- Protect/Sludge Bomb
- Giga Drain
This is my favourite set, as it is really bulky. Leech Seed recovers health while dealing damage at the same time. Synthesis is for instant recovery when you get too low. Protect allows you to stall (useful for leech seed damage/recovery), while sludge bomb is STAB. Giga Drain is mandatory STAB so you're not taunt bait and for more recovery. Be warned that if you do run protect (like me) you are hardwalled by every grass type and sap sipper pokemon. Sludge Bomb allows you to not be dead weight in these matchups and is usually preferred.
EVs are weird but here's why: 92 Spe outruns max speed base 50 pokemon, and the rest are allocated into bulk so it walls more stuff, with slight investment into SpA so Giga Drain (and Sludge Bomb if you use it) hit a little harder.
There is also a decent physical attacking Venusaur. It is useful for the surprise factor (it swept half my team, including my special wall, before I realized it was physical). 100 Base Attack is usable, although the special set or stall sets are usually better. The only reason to use it is if you want the surprise factor, or if you lack other physical pokemon (meaning you don't have Breloom, Ferrothorn, Trevenant, or Tangrowth who are all usually better as physical grass types). I'm not sure of the exact moves/EVs but I'll give it a try:
Venusaur-Mega @ Venusaurite
Ability: Thick Fat
Shiny: Yes
EVs: 4 HP / 252 Atk / 252 SpD or 252 Atk / 252 Def / 4 SpD
Adamant Nature
IVs: 0 SpA
- Synthesis/Leech Seed
- Curse/Earthquake
- Power Whip
- Knock Off/Earthquake
First move is recovery as usual. Second move is either curse (boosts attack and defense really high, making Mega Venusaur hard to kill) or EQ if you dont want the boosts. If running EQ, use the second EV set for more physical bulk (Curse boosts Def so EVs are unnecessary when using Curse). Third move is powerful STAB. Final slot is for coverage. Knock Off is for tremendous utility in removing items or EQ hits steel types and fire types hard, taking advantage of Thick Fat and hitting types that threaten grass.
Corrections/advice appreciated, but I just wanted to put this out there. Overall Articuno's write up was good and S Rank is correct as it has a variety of sets that all work well and it is mandatory on every grass team. ^_^