The general vibe I've gotten from your skeleton is that your describe Sylveon itself (and pretty well) but not as much as what is it like in metagame - the latter is better, as the former could theoretically be determined just from looking at its Serebii's page. You're also a bit simplistic at times.
Overview
-When you write it up, I wouldn't say power that's hard to compete with. Just say it hits very hard - more concise and less misleading (e.g. Rampardos has power that's hard to compete with but it sucks)
-It does not have a decent selection of coverage moves
base 95 HP is actually ok. It's the mediocre Defence that lets it down.
-I would mention bad speed and excellent special bulk separately.
-If you're going to mention support is necessary, you must state what type of support this is
-Mention Steel-types somewhere
-What type of teams does Syvleon fit on?
-I wouldn't mention decent coverage moves; they're actually not that good
Moves
-must mention spread with Hyper Voice
-mention Hyper Voice hits through Sub here, not in Usage Tips
-Hidden Power provides coverage against Steel-types - you only said that for HP Fire.
Set details
Be more specific as to what it does; this is too vague
Should mention that as Syvleon will mainly be using Hyper Voice, it doesn't suffer much from the inability to switch moves
Remove surviving Jolly LO Bisharp - that is incorrect. Not sure why Lolk said to include it.
252 Atk Life Orb Bisharp Iron Head vs. 56 HP / 200 Def Sylveon: 361-429 (104.6 - 124.3%) -- guaranteed OHKO
If using Sylveon with Trick Room, have 0 Spe IVs
252 HP Evs does not give it
much more useable Special bulk, just more. I would also prefer you to list the changes in KOs provided by 252 HP instead of just saying "many more"
Should also mention alternate spread of 176 HP / 252 SpA / 80 Spe if using Syvleon with Tailwind - under Tailwind, 80 SPe lets it outspeed base 110 Pokemon like Mega Diancie
Usage Tips - this should be more thorough
-don't mention Hyper Voice through Sub here
-Spamming Hyper Voice 99% of the time to inflict as much damage as possible
-no need to mention trouble dealing with Poison and Steel types because of Hyper Voice (spamming Hyper Voice is no excuse - use your teammates or coverage attacks)
-How will you take down the threats to Syvleon? Teammates
-How will you bring it onto the field
-When do you not use Hyper Voice but one of it's other moves
-Should also mention that it should be expected to take an attack before attacking thanks to its Speed, it's special bulk will help out here
-Could mention how to use Sylveon in conjunction with support, especially considering that you've mentioned it in Overview
Team Options
-I wouldn't say base 60 speed can be viable both in and out of TR, as Speed by itself is not going to make a Pokemon unviable outside of TR (and 60 is bad outside of TR, look where non-mega Metagross is). I would say base 60 speed is helpful under Trick Room, then mention TR
-mention examples of TR users when you mention TR. When you mention Cress, also mention Helping Hand support
-with Fake Out, mention that it helps Syvleon fire off Hyper Voice
-mention examples of Intimidate and burn abusers
It's the latter as to why it pairs well with redirectors. spread moves not threatening Syvleon is not a main reason to use them
Remove that bold stuff; that's a big and debatable statement to say they are better at checking steel-types in a 2v2 setting. Just add those examples with Heatran and Conkeldurr.
-mention Ground-types somewhere; it's the Ground-type that pairs best with Fairy - it hits all the types that resist Hyper Voice super-effectively. Then give examples
OO
-Mention Shadow Ball here as it's your best attack against Aegislash
-Mention LO and Pixie Plate as alternatives to Specs if you really want to be able to switch moves
-say not running Specs makes Syvleon hit weaker than Mega Gard, which is one of its major perks over Mega gard. I wouldn't jump it all the way to being outclassed
-Contrary to what Haruno said, I would mention Hyper Beam here, and that's more to describe its flaws rather than to encourage its use. You can of course still mention it hits really hard though
Checks and Counters
-Steel-types should watch out for HP Ground and/or Fire
-With bisharp, must mention that Hyper Voice OHKOes
-Poison types should watch out for Psyshock
-Physical attackers that can tank a Hyper Voice and hit hard, not physical attackers without super effective moves (that implie they can take it out
because they don't have super-effective moves). I would not mention Gyarados as it doesn't hit hard enough (it's unlikely to 2HKO). Could also mention Mega Kang has an almost guaranteed OHKO if has Double Edge and an Adamant nature
-Sleep immobilies everything; I wouldn't mention it specifically as a check. What I would do however is say, when mentioning Poison-types, that Mega Geng and Venasuar threaten Sylveon with their Poison-type STAB, where as Amoonguss threatens it with Spore
-Fire-types belongs under typing advantage, not miscellanous
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