I'll just follow normal rules and stick to just one type, which would obviously be Ice - my favorite type.
My gym would probably be the 7th gym.
The city which my gym resides will be at a slightly higher altitude than the other cities of the region - making it naturally distant. Several houses will be present - but there won't be any major infrastructures apart from the Gym and a museum dedicated to Ice and Water Legendary Pokemon - namely Articuno, Suicune, Regice, Kyogre, Palkia, Manaphy, Phione, Keldeo and Kyurem. A shady figure will be lurking in front of the museum - perhaps someone from an evil organization?
The Gym will be inaccessible to the challenger at first - and a trainer will inform the player that I have gone to a nearby mountain as local Ice-type Pokemon which reside in the mountain have gone restless. The challenger will then find me on top of the mountain peak, where Articuno will be there, communicating with me. Articuno will sense the challenger's presence and fly away. Then, I notice that the challenger has arrived.
My appearance would be like that of my profile pic. Slightly small in appearance, but with a cheeky smile and short brown hair.
'Ah, you must be (challenger). It's nice of you to visit me here. Don't look so surprised that I know your name! I've heard all about your successful victories over the other Gym Leaders, and I assumed that you will come here eventually for my badge. You're lucky to have seen Articuno, however. Beautiful isn't it? Not many people witness me communicating with Articuno. It doesn't usually appear here unless it wants to forewarn us of a great peril. Something malevolent is approaching us, and Articuno have come to inform us in advance...
But let us not dwell on that matter for now. Tell me, do you like Ice-type Pokemon?'
Yes: 'Oh good! I feel like we're developing a certain kinship already! I expect it to show up in our upcoming battle.'
No: 'I see. Forgive my regulations, but I make it a top priority that my challengers have at least one Ice-type Pokemon in their party when they come to challenge me. There are a lot of Ice-type Pokemon in this mountain as you probably know already, so I suggest you try and befriend one before coming to my gym.'
'I better get going now. It would be extremely rude of me to leave a skilled challenger such as yourself to wait for longer than they have to. Join me at your leisure, (challenger). Farewell for now.'
Upon entering the gym, the challenger will find him/herself in a very large, chilly garden. The Gym Leader's chamber can be found at the far end of the garden, but a giant lake with large currents will be blocking the way. Due to the large currents, it will be impossible to surf across the lake, and instead, the challenger must locate 5 different Ice Pokemon in the garden (Smoochum, Cubchoo, Sealeo, Vanillish and Cryogonal) - and bring them all to the edge of the lake, so that they can freeze the lake and allowing the challenger to access the Gym Leader's chamber. The garden will contain a slightly complex maze and trainers will be scattered throughout the Gym.
When the challenger has reached the Gym Leader's chamber:
'Wow, I really didn't expect to see you so soon! Usually challengers take around a couple of hours on average to conquer the maze, but you sure seem pretty intelligent. Let me formally introduce myself. My name is OOO and I specialize in Ice-type Pokemon. Ice is known to be very fragile, but it is the beauty that is concealed within the fragility that makes Ice Pokemon so elegant! I see you have brought (challenger's Ice-type Pokemon) with you. Good! I can't wait to see how it performs in battle! Alright, enough talking. Let's get this show on the road!'
The Team:
Mamoswine @ Focus Sash
Ability: Thick Fat
Jolly Nature
- Earthquake
- Ice Shard
- Icicle Crash
- Stealth Rock
Aurorus @ Choice Scarf
Ability: Snow Warning
Modest Nature
- Blizzard
- Earth Power
- Freeze-Dry
- Thunderbolt
Froslass @ Leftovers
Ability: Snow Cloak
Timid Nature
- Hail
- Hidden Power (Ground)
- Ice Beam
- Shadow Ball
Weavile @ Life Orb
Ability: Pressure
Jolly Nature
- Ice Shard
- Icicle Crash
- Knock Off
- Low Kick
Cloyster @ White Herb
Ability: Skill Link
Adamant Nature
- Icicle Spear
- Razor Shell
- Rock Blast
- Shell Smash
Glaceon @ Brightpowder
Ability: Snow Cloak
Modest Nature
- Hidden Power (Ground)
- Ice Beam
- Shadow Ball
- Wish
When the challenger wins:
'Your skills have surely surpassed mine. Kudos to you!'
When the challenger loses:
'A loss can be bitter - but don't feel bad about it. Concentrate on improving yourself, and you'll see the light eventually'
After the battle:
'I haven't had to take this jumper off during a battle for a long time. Cheeky as it sounds, but you are one fiery trainer. As the proof of your victory, I shall grant you-'
*EXPLOSION*
'...Are you alright? It seems that Articuno's warning was to be anticipated sooner than I expected it to be. Come, (challenger). Let us find out the source of this commotion...'