Hi Atyl,
So, just from team preview, you have pretty much legitimately no reason to run Galvantula. Blissey, Forry, and Slowking are designed to take hits and don't really need to be outspeeding anything. Espeon is likely going to be the fastest of the twelve possible mons with a scarf equipped. Sharpedo literally has Speed Boost. So just right there I can tell you that Galvantula is frankly redundant for you and a waste of a teamslot, especially if you are using it as a suicide hazards lead. It's simply silly.
Unfortunately, it is quite difficult to tell what the "aim" of your team is here. You have some vaguely offensive cleaner mons (Espeon, Sharpedo), two sort of pivots (Forry, AV Slowking), a stall mon (Blissey) and a suicide lead (Galvantula). I hope you can see what I mean when I say that this team doesn't have a lot of coherency.
I assume, just by the descriptions that you've written, that this is an attempt at what we would call a "balance" team. If you are unfamiliar with the jargon, a balance team is typically one that has, in roughly equal measures, ways to respond to common threats offensively and defensively. It stands in contrast to the other extremes, Hyper Offense and Stall, by virtue of how you play the game - put simply, Hyper Offense games are all about hitting hard and fast while Stall games are about keeping the pace of a match deliberately slow and outlasting the opponent. There are other various "archetypes" but, for the moment, they're not terribly necessary to elaborate on them. I figured you were attempting to create a "balance" team because of the way you combined intuitive "attacking side" walls/checks (i.e. 'I need a special wall, so I'll take Blissey, I need a physical wall, so I'll take Forretress, etc.) Unfortunately, this is not a particularly good way to build a team.
For reference, as I assume you are a newer player (and don't worry about this, RMT is a decent forum to start out in as many of the likely responders will be eager to help), there are two general ways to teambuild. The first is to simply pick a mon and build around it (and that's what I'll try to do with your team). The second way is more cerebral, thinking about how to respond to various threats and keep momentum through switches and punishments that are available. The latter is a bit harder, but often creates the better teams - though the former is no slouch either if done correctly.
Alright, to begin with the rate, I'll start by saying that I'll try to keep as much the same about your team as possible while drafting up what I think is a squad with more coherency and a more obvious common goal. In this sense it'll be to be rather standard, able to respond to common threats that you'll find on the ladder, not particularly excelling at anything in particular but not suffering disproportionately against anything common either.
First move will be to get rid of Galvantula entirely. I'm not a huge fan of Galv to be honest, especially with the decent amount of good and offensive defog users in the tier. This makes it difficult to say, stay in and taunt a defog because you could lose a mon in the process. Sticky Webs are tough to get up multiple times because Galvantula is frankly garbage, doesn't necessarily scare out that much nor can he take a hit. So we'll just remove him.
You're using Mega Sharpedo, and as one of the best megas in the tier, I'd like to keep him on the team. So I'll try and tweak the team around the idea of a Sharpedo sweep and make adjustments as necessary. With Galvantula gone, we have a free slot, and looking at the rest of the team I'd like to move SR into this spot and let Forretress start using Spikes. Mega Sharpedo is unique in that he can hit almost as hard as some wallbreakers while still being able to easily get +1 speed. Definitely a scary mon. With a layer of spike and SR up his job becomes that much easier, so it'll be quite cool to have multiple hazards chipping away at the opponent while you use the rest of a balanced team to continually force switches. I'd like to move SR from Forretress because if he has both hazards and spin he's going to be under way too much pressure throughout the match.
So we have a few things in mind now. We want to support Sharpedo and have SR in this empty slot. Sharpedo can't take a single grass, electric, fairy, bug or fighting hit and hates pretty much any non-resisted priority in tier (this is primarily ESpeed). Additionally, Sharpedo can't break through exceptionally bulky physical walls, with something like MAggron as a benchmark that we'll want to be broken before Sharpedo starts revving his engines. So we can patch a few of these weaknesses pretty quickly by using Cobalion. Cobalion's fighting/steel typing, great speed tier, access to SR and ability to dent common walls in the tier (Snorlax, MAggron, PhysDef Florges) means he's a decent partner to Sharpedo. Here's the set I like for your Cobalion:
Cobalion @ Leftovers
Ability: Justified
EVs: 4 HP / 252 Atk / 252 Spe
Jolly Nature
- Stealth Rock
- Close Combat
- Volt Switch / Taunt
- Iron Head
I sort of like taunt on this set because it really helps you keep up hazards, but Volt Switch provides really good momentum as well. Choose whichever fits your personal preference.
Next I think we should replace Blissey with something that provides you a bit more utility, better typing to support Sharpedo and a little more offensive presence. Blissey is a bit of a momentum sinker on teams that aren't stall oriented, so it's not really fitting to be paired with Sharpedo very often. I think Florges does a lot in this spot. It helps deal with fighting types (Heracross the notable example) as well as some bulkier mons that will always impede Sharpedo's sweep if they aren't worn down (Mega Blastoise with Aura Sphere coverage). Use the following set:
Florges @ Leftovers
Ability: Flower Veil
EVs: 252 HP / 252 Def / 4 SpD
Bold Nature
- Wish
- Protect
- Moonblast
- Aromatherapy
I chose Florges over Aromatisse because it functions a bit better as a mixed wall, and I'm assuming you want a "special wall" on your team.
For Forretress, I think you can keep the set the same (sans putting Spikes over Stealth Rock as mentioned before) but switch to Leftovers. The additional recovery is pretty good on Forry, and with Cobalion you have a decent check to most Mega Beedrills, so the chip damage isn't super important, especially because after Sharpedo will almost always be able to OHKO MBee.
I don't really like Scarf Espeon. It's power and offensive typing is a bit lacking for a scarf user. While it's nice to surprise Mega Beedrills every now and then, overall I don't find it a terribly consistent strategy. With no Ice Fang on your Sharpedo set, I'm thinking you may have a bit of trouble with Salamence, particularly the intimidate sets as they can tank a hit from Sharp and OHKO back. I'm tempted to put an offensive Whimsicott here, which provides you a check to Dragons (though not in particular Salamence, because it often carries Fire Blast) and a way to stop setup sweepers (so they can't say, boost past Sharpedo rendering him inert). I think for now that works, but I'll sleep on it and see if a better idea comes to mind. This set will outspeed any non-scarf dragon in the tier and be able to deal a ton of damage:
Whimsicott @ Life Orb
Ability: Prankster
EVs: 4 Def / 252 SpA / 252 Spe
Timid Nature
- Moonblast
- Energy Ball
- Encore
- U-turn
This set also provides a good check to Suicune, who, as a massively bulky water wall will give you issues in any attempted sweep. A more defensive set could be viable, but my changes to the team were mostly in the "middle" of offensive/defensive utility I think so it could be just more fun to play with a more offense oriented option here.
Finally, I would change the Slowking set. Without MPidg in the tier you don't really need Assault Vest any more just IMO. The standard CM set is really good, and with Cleric Support you can get second and third chances to set up for a sweep from a different mon (for example, healing off Toxics or something)
Slowking @ Leftovers
Ability: Regenerator
EVs: 248 HP / 252 Def / 8 SpA
Bold Nature
- Calm Mind
- Scald
- Psyshock
- Slack Off
Let me know what you think of the suggestions and I'll gladly come back to any of them if you'd like and reconsider. I've said this before but I tend to write and think at the same time, so there are definitely chances that there are oversights here, but I feel that on the whole this team is a lot more cohesive than what you had before and much more able to achieve its aims. Sharpedo is a really fun mon, so given the right support I think you can definitely do well on the ladder and in room tournaments where you can refine the team even more to your own liking.