Guess the gym leader

[The Traveller]

Marlon?

The only male specialist of his type until Gen. IX

 

[guzmania]

Bede iirc

he is a very forgettible gym leader and specilizes in water

the "forgettable" part is subjective, and "male water-type gym leader" isn't a tiny category of characters i would say Juan

This character composes one-half of Elite Four members specializing in their specific type. Legend has it they're a messy eater.

edit: my brain blipped when i wrote this and for some reason thought it was supposed to be any character instead of a gym leader LMAO.... won't put a new one since it's been solved, but my apologies for the mishap!

 

[The Traveller]

Bede iirc

Whoops, I forgot about Bede and Ortega… I was thinking of Falkner (only male Flying-type specialist until Larry), but your answer also fits the clue perfectly!

As for my own guess…Glacia?

This Gym Leader has a family member who is an Elite Four member.

 

[c la fet]

Janine ?

My best guess is candice

It's not Candice but you're close