OP here I like all these ideas
Now to post a Egg group-based Gym team
Starting with... Undiscovered! Or Baby Pokemon.
>The Gym Leader is an avid breeder, thus his Pokemon know Egg moves, a couple have Hidden Abilities, and have favourable stats. Despite passing the tests for being a Gym Leader he uses rather tough moves to make up for his team's whole baby thing.
-Pichu, Lightning Rod, Lv. 16 (Hidden Power Ice, Sweet Kiss, Thunder Shock, Nasty Plot)
-Mantyke, Water Veil, Lv. 16 (Hidden Power Ground, Confuse Ray, Water Pulse, Bounce)
-Chingling, Levitate, Lv. 17 (Hidden Power Fighting, Confusion, Hypnosis, Icy Wind)
-Togepi, Super Luck, Lv. 17 (Hidden Power Rock, Metronome, Mirror Move, Sweet Kiss)
-Tyrogue, Guts, Lv. 18 (Hidden Power Ghost, Mach Punch, Fake Out, Bullet Punch)
-Munchlax, Thick Fat, Sitrus Berry, Lv. 20 (Hidden Power Ground, Charm, Chip Away, Shock Wave)
Despite the team having scary movesets, you're given the materials to match 'em, plus you may have a couple evolved Pokemon too.