For a beginner, you really aren't that bad at this. Let me give some pointers on what you could fix up.
Infernape
Perfect Infernape. Nothing to say here.
Rotom
Okay, this Rotom is kind of weird, but you might be able to pull it off. A Chesto/Rest strategy could potentially work, but it only works once and uses a moveslot. If you want to keep it, you definitely can, but my advice would be to switch out Rotom for something else. If you want to keep it but aren't sure how to tweak it, I have a few ideas.
- Give it a Choice Scarf. A scarfed Trick is like an infinite Encore.
- Switch Rest for Hidden Power Ice/Fire, and maybe switch Thunderbolt for Volt Switch.
- You could set up a Will-O-Wisp/Hex strategy for it, since you trained it to be tanky.
That being said, Rotom is mainly used as a lead and is not very useful on this team.
Bronzong
I like the strategy, but you're not really using a good Pokémon for this role. Instead, use Skarmory:
Scarmory @ Leftovers
Ability: Sturdy
EVs: 252 HP / 252 Def / 4 SpD
Impish Nature
- Spikes/Roost
- Stealth Rock
- Toxic
- Roar
Now there's a good physical tank that can set up some hazards pretty reliably.
Chansey
Here's Chansey's problem: you trained its Defense. Chansey can't take physical hits whatsoever. Either invest EVs in HP and abandon Chansey when a physical attacker comes, or use this Blissey:
Blissey @ Focus Sash
Ability: Natural Cure
EVs: 252 HP / 252 SDef / 4 Spd
Gentle Nature
- Toxic
- Soft-Boiled
- Hidden Power [Ground]
- Counter
This Blissey can KO any physical attackers and tank any special attackers. HP Ground is for Poison and Steel types that can't be poisoned and in case of Taunt.
Donphan
Good idea with Donphan. Keep it if you want. I personally prefer Excadrill.
Excadrill @ Leftovers/Air Balloon
Ability: Mold Breaker
EVs: 252 HP / 252 Atk / 4 Spd
Adamant Nature
- Rapid Spin
- Stealth Rock
- Earthquake
- Rock Slide
Excadrill just seems to fill the place a little better.
Garchomp
Pretty much a perfect Garchomp. Only suggestion is to replace Iron Head for Poison Jab for coverage.
So that's what I suggest for you and your team. It's really great overall, and as for a rating, I'd give its current condition a solid 7. If you have questions, go ahead and ask them, and heck, a BA would be nice. :)
Anyway, hope I helped!
