I'll shift to annoy you.

[{Galvantula}]

[spoiler= Monsters]
Shift Knight
EARTH / Level 4 / Warrior/Effect / 1900/0
During your End Phase: switch the ATK and DEF of this card. While this card's ATK is higher than it's DEF; this card inflicts piercing damage. While this card's DEF is higher than it's ATK; this card can not be targeted for an attack while in attack position.

Shift Caster
EARTH / Level 3 / Spellcaster/Effect / 1200/1500
During your Standby Phase: switch the ATK and DEF of this card. While this card's DEF is higher than it's ATK; once per turn: you can switch the ATK and DEF of 1 other "Shift" monster you control. While this card's ATK is higher than it's DEF; if another "Shift" monster's ATK and DEF are switched: you can send the top card of your Deck to the Graveyard; draw 1 card.

Shift Sentry
EARTH / Level 4 / Rock/Effect / 0/1800
During your Standby Phase: switch the ATK and DEF of this card. While this card's DEF is higher than it's ATK; other "Shift" monsters you control can not be targeted for an attack. While this card's ATK is higher than it's DEF; once per turn: if another "Shift" monster you control would be destroyed by battle, you can send 1 card from your Hand to the Graveyard; it is not destroyed.

Shift Gardna
EARTH / Level 4 / Warrior/Effect / 800/1300
During your End Phase: switch the ATK and DEF of this card. While this card's DEF is higher than it's ATK; when another "Shift" monster is summoned, draw 1 card. While this card's ATK is higher than it's DEF; you do not take battle damage from a battle involving another "Shift" monster you control.

Shift Support Bot
EARTH / Level 3 / Machine/Effect / 0/0
If you control a "Shift" monster: you can Special Summon this card from your Hand. During the End Phase: you can send 1 card from your Hand to the Graveyard; switch the battle position of another "Shift" monster you control.

Shift Golem
EARTH / Level 4 / Rock/Effect / 1600/1100
During your End Phase: switch the ATK and DEF of this card. While this card's ATK is higher than it's DEF; you can send 1 card from your Hand to the Graveyard; reduce the ATK or DEF of 1 monster on the Field to 0. While this card's DEF is higher than it's ATK; if another "Shift" monster you control would be sent to the Graveyard, you can return that monster to your Hand instead.
[/spoiler]
[spoiler= Spells]
Quick Shift
Quick-play / Spell
Banish the top card of your Deck; Switch the ATK and DEF of 1 "Shift" monster you control and draw 1 card.

Shifting Fortress
Field / Spell
Once per turn: you can select one "Shift" monster you control. If that monster's ATK is higher than it's DEF: you can draw 1 card. If that monster's DEF is higher than it's ATK: you can destroy 1 card on the Field.

Shift Contract
Normal / Spell
Send 1 "Shift" monster you control to the Graveyard. If that monster's ATK was higher than it's DEF: destroy 1 card on the Field and add "Shift" monster from your Deck to your Hand. If that monster's DEF was higher than it's ATK: add 1 "Shift" monster from you Deck to your Hand and inflict 800 damage to your opponent.
[/spoiler]
[spoiler= Xyz]
Shift Vanguard
EARTH / Rank 4 / Warrior/Effect / 2400/1900
2 level 4 EARTH monsters.
While this card has an Xyz Material(s): during your End Phase; switch the ATK and DEF of this card. While this card's ATK is higher than it's DEF: you can detach 1 Xyz Material; switch the ATK and DEF of 1 "Shift" monster you control and destroy 1 card your opponent controls. While this card's DEF is higher than it's ATK: once per turn; you can detach 1 Xyz Material; negate the Summon of a level 3 or lower monster you opponent controls and destroy it, then switch the ATK and DEF of 1 other "Shift" monster you control.

Shift Guardian
EARTH / Rank 3 / Warrior/Effect / 2000/2000
2 level 3 monsters.
You can detach 1 Xyz Material; switch the ATK and DEF of 1 monster on the Field. Other monsters you control gain 300 ATK for each of this card's Xyz Materials.
[/spoiler]

I'd appreciate feedback.

[motorcyclez]

Wow, really nice and original idea. Can really annoy opponents, but even still, Level 4, with 2100 ATK? Even if its ATK and DEF switch you can't target it, ATK should be lowered a bit to 1950 or something

[{Galvantula}]

1900 in that case. I hate 50s.

[Duck_Sauce]

This, my friend, is a fantastic idea. I'd like to see the archetype continue.

ATK & DEF Balance: 10/10
Effect Balance: 9.5/10
OCG: 10/10
Overall: 9.7/10

[{Galvantula}]

Turned it into an archetype!

[motorcyclez]

You just keep finding ways to make this better, don't you. The only thing that would make this better is a synchro, tuner, and 1 or 2 traps. This was well done. I hope you make more.