Psychic

I usually love Psychic-types in general, so why not? Xatu, Gardevoir, Meowstic, Raichu, Mega Gallade. If I should have 3, I'd keep Xatu, Mega Gallade, and Raichu

I would be a Johto Dark type Gym leader. My pokemon would be Mightyena, Umbreon, and Honchkrow.

Normal type (can't get over eevee)

Maybe I would choose Poison. My team would be Muk, Venipede, and Toxtricity.

Electric types cause PIKACHU or flying type cause that would be really cool! Has there ever been a dragon type gym (besides Raihans)?

If I had to choose I would choose water. And I would use pirimerina, lapras, and wishy washy. But I like pokemon from different types so I wouldn't be a gym leader.

Bug.

I love Araquanid, and have fond memories of using Galvantula and Volcarona in Gen 5 OU.

Araquanid and Galvantula can set-up Sticky Webs (IMO the best stage hazard). Araquanid can also reflect Stealth Rocks with Magic Coat. Volcarona can easily sweep, and Armaldo learns rapid spin.

Dragon type.

One of the most op types in the game it got nerfed when fairy type was introduced but it still is very powerful.

My gym leader team

Duraludon: to cope with the fairy weakness

Dragapult

Hydreigon

Kommo o

Tyranitar

Garchomp

Bug type