My team for Shield is as follows (FYI, my entire team can be caught throughout the main storyline):
My Starter, 1st Pokémon, Cinderace (Johana Blaze) can be found when choosing your first Pokémon. She (Yes, I DID get a female starter 1st try) has the ability Blaze and is holding Charcoal. Her moves are Zen Headbutt, Pyro Ball, Double Kick, and Iron Head. Another move I used on her was Flame Charge (although she's a speedy one already).
I always choose the Fire-type, ever since XY. Plus, the 1st gym is Grass.
My 2nd Pokémon,Coalossal (Full Steam), can be found on Route 3. She has the signature ability of Steam Engine and is holding the Hard Stone. Her moves are Heat Crash (although Flame Charge can work with his ability), Heavy Slam, Rock Slide, and Body Press. Another move I used on her was High Horsepower.
I thought she looked cool design-wise and I wanted to test out its signature ability.
My 3rd Pokémon, Grimmsnarl (Gremlin), Can be found in Glimwood Tangle. He has the ability Prankster (even though I rarely use status moves) and is holding Black Glasses (EDIT: I have found a G-Max version, but with the Frisk Ability. He now has adopted my old one's item.). His moves are False Surrender (its signature), Play Rough, Drain Punch, and Leech Life. Another move I used on him was Spirit Break (another signature) and Brick Break.
At first, I was indifferent about him. But, I wanted to test out the new Dark/Fairy dual-type.
My 4th Pokémon, Corviknight (Dark Knight), can be found early on Route 1 or 2 (I can't remember). He had the ability Unnerve and was holding Metal Coat (Because I found a Gigantimax one in the Wild Area with its HA, Mirror Armor. He now holds Sharp Beak). His moves are Fly, Iron Head, Rock Smash, and Façade. Another move he had was Brave Bird (if you're feeling gutsy).
Almost everyone tries out the regional bird when they start out in their "adventure". I really like Steel-types (as well as Fire-types, hence my starter), which is why I chose him on my team.
My 5th Pokémon, Frosmoth (Mothreez), (kinda named after Mothra, but more Freeze) can be found on Route 8 just before the sixth Gym. She has the Shield Dust ability and is holding Never-Melt Ice (EDIT: I have found a shiny variant, but with its HA of Ice Scales. She now has adopted my old one's item.). Her moves are Hurricane, Giga Drain, Bug Buzz, and Ice Beam.
Again, new dual-type of Ice/Bug. Also, Snom is soooo Cute! :3
She reminded me of Volcarona (on my previous favorites).
My 6th Pokémon, Eternatus (Necrozma 2.0) can be found and caught before you challenge the E4 in thee main storyline. It has the ability Pressure and is holding Black Sludge. Its moves are Venoshock, Flash Cannon, Flamethrower, and Dynamax Cannon.
Necrozma-looking dude. What more can I say.
For to defeat the Gym leaders, here are the Pokémon I used:
For Milo, I used my starter, Raboot, and her Fire-type moves to defeat him.
(See reasoning for Cinderace above) Self-explanatory!
For Nessa, I caught a Gossifleur (Cotton Swab) on Route 3 and evolved her into Eldegoss. She held the Rose Incense and used her plethora of Grass-type moves to defeat her. She also had the Cotton Down ability.
She had the new ability I really like.
For Kabu, I used my Carkol and her Rock Slide to defeat him.
(See reasoning for Coalossal above)
For Allister, I used the traded Impidimp/Morgrem and its Dark-type moves to defeat him. Also, I used a Runerigus (Heiroglyphia) and her Ghost-type moves. I ended up winning due to my Coalossal waking up from sleep and knocking out his Gengar.
(See reasoning for Grimmsnarl above).
For Opal, I used my Corviknight and its Steel-type moves (also used my Cinderace's Flame Charge to knock out her Mawile) to defeat her.
(See reasoning for Corviknight above)
For Melony, I switched between using my starter and my Coalossal's Fire- and Rock-type moves respectfully to defeat her.
Revisit Coalossal and Cinderace's reasonings.
For both Piers and Raihan, I had to switch out everytime I KOed any one of their Pokémon, but:
I mainly used my starter's Double Kick, Frosmoth's Bug Buzz, Coalossal's High Horsepower, and Grimmsnarl's Spirit Break/Play Rough to defeat Piers.
I mainly used my Frosmoth's Ice-type moves, starter's Double Kick, Coalossal's High Horsepower, and Grimmsnarl's Brick Break and Play Rough. Also, I used my Dragapult (Jetstream). He has the Infiltrator ability and is holding the Dragon Fang. His moves are Steel Wing, Breaking Swipe, U-Turn, and Phantom Force.
The above 2 can be reasoned with just two words "My team".
For the Leon battle, I used these 6 Pokémon:
Toxtricity Amped-form (Air Guitar) She's holding Magnet and having the Punk Rock ability. Her moves are Shift Gear, Overdrive, Poison Jab, and Boomburst.
My starter, Coalossal, Corviknight, Frosmoth, and Grimmsnarl (I think I swapped one of the 4 Pokémon in this sentence with my Dragapult.).
Toxtricity has the unique dual-typing of Electric/Poison that I really wanted to test out.
Dragapult has a very unique design (I was going to nickname him Casper, but Casper is a friendly ghost, not a sweeper XD). Also, I wanted to see what a non-legendary Ghost/Dragon Pokémon can do.
Aaaaaaand, that's ALL I have to say....about that.