Basically :
- Giving the first 2 regis more uses cases with more resists,
- Giving the og regis a strong sig move to be slightly more threatening without buffing Atk/SpA,
- Small buffs to the galar regis for consistency
- Slighty memey changes to Regigigas.
If this adjustement wins, change every "80" in the winning regis's stats to 100 (and switch Clear Body to a type related ability if possible)

Regirock
Stats: 100 (+20) / 100 / 200 / 50 / 100 / 50
(580 -> 600 BST)
Abilities : Peak Rock Body (User now resists Electric, Bug and Dark) /
Sturdy
Added Moves : Pain Split, Spikes, Headlong Rush
New Signature Move : Mantle Shaper
Rock / Physical / 100 BP / 16 PP / 100 Acc / Contact / Recovers 50% of damage dealt.
Dark resist is meant to synergise with Body Press.

Regice
Stats: 100 (+20) / 50 / 100 / 100 / 200 / 50
(580 -> 600 BST)
Abilities : Deep Frozen Body (User now resists Dragon, Ground and Fire (Fire becomes a resist instead of a weakness) ) /
Ice Body
Added Moves : Pain Split, Mirror Coat, Calm Mind, Earth Power
New Signature Move : Freezing Age
Ice / Special / 100 BP / 16 PP / 100 Acc / No tags / 100% chance to raise user's Defense by 1. Hits both opponents.
Now has 4 resists and only 3 weaknesses. Earth Power is given to hit Fire types.

Registeel
Stats: 100 (+20) / 75 / 150 / 75 / 150 / 50
(580 -> 600 BST)
Abilities : Hollow Iron Body (User now resists Ghost, Dark, and Sound moves (Sound moves are resisted regardless of original type) ) /
Light Metal
Added Moves : Pain Split, Metal Burst, Rapid Spin, Minimize (banned)
New Signature Move : Unbreakable Steel
Steel / Physical / 120 BP / 16 PP / 100 Acc / Contact / -3 Priority (similar to Beak Blast). Takes halved damage before attacking.
Small changes to Registeel because it needs less changes to be good. Sig move is a Heavy Press replacement (relevant in a meta full of legendaries). Pain Split could be too much ?

Regigigas
Abilities : Slow Start /
Weak Start (On switch-in, this Pokemon's Attack and SpAtk are halved for 5 turns)
Added moves : Explosion, Stealth Rock, Spikes, Bind
New sig move : Crush Grip
Normal / Physical / 130 BP / 16 PP / 100 Acc / Contact / Frees user from hazards/bind/Leech Seed. User yawns.
Regigigas gets a few tools to work as a Suicide Lead and its sig move becomes Gigaton Hammer with 30 less BP + Rapid Spin. (Regigigas with Slow / Weak Start has less Atk than Tinkaton). Easily shut down by taunt but usable.

Regieleki
Stats: 100 (+20) / 100 / 50 / 100 / 50 / 200
(580 -> 600 BST)
Abilities: Transistor /
Lightning Rod
Added moves : Pain Split, Hidden Power, Parabolic Charge, Ion Deluge
Changes made for consistency with the other regis. Hidden Power is good enough for coverage.

Regidrago
Stats: 200 / 100 / 50 / 100 / 50 /
100 (+20) (580 -> 600 BST)
Abilities : Dragon's Maw /
Levitate
Added moves : Pain Split, Hidden Power, Dragon Rage, Psychic Fangs
Changes made for consistency with the other regis. Sheer Force would fit it more but 100 Speed + Dragon Energy is scary enough to not give it another good set. Levitate is picked instead because of the many Dragon-types with Levitate or a secondary Flying type (also because it levitates).