The first synchro monsters to hit the TCG did so in Starter Deck 2008, namely Junk Warrior, Gaia Knight, the Force of Earth, and Colossal Fighter. Just a few weeks later, the warriors would no longer hold a monopoly over this new game mechanic.

2008
Synchro Monsters (Japanese: シンクロモンスター Shinkuromonsutā; usually abbreviated Ｓ シンクロ モンスター since Duelist Alliance) are a type of Monster Card, first released in Starter Deck 2008. The color of their card frame is white. These cards are placed in the Extra Deck.

1 – During your Main Phase, you can declare a Synchro Summon when the combined total Levels of 1 face-up Tuner Monster and any number of other face-up monsters you control are equal to the Level of the Synchro Monster you want to Synchro Summon.

Performing a Synchro Summon does not start a chain. You cannot use face-down monsters to perform a Synchro Summon.

Yes you can normal summon a monster and perform a fusion summon in the same turn. You must have a tuner monster on the field and then one or more non tuners on the field, whose total levels are equal to the levels of the Synchro monster you are attempting to Synchro Summon.

Kaiba, Kaiba uses this card in his Duel with Yugi Muto. He Synchro Summons it using “Sage with Eyes of Blue” and “Blue-Eyes White Dragon”. When Yugi tries to destroy this card with “Thousand Knives”, Kaiba Tributes this card via its own effect to Special Summon “Azure-Eyes Silver Dragon” in its place.

Xyz Monsters can be revived with cards like Monster Reborn and Call of the Haunted, just like any other monster, but if you do that, they don’t have any Xyz Materials attached to them and you can’t use their effects.

Double Tuning is also possible with some Synchro Monsters that do not specify that the monsters other than the required Tuner must be non-Tuners. Therefore, up to 5 Tuner monsters can be used for its Synchro Summon.

A player can perform any number of Synchro Summons per turn.

The new Pendulum Summon mechanic allows you to Special Summon monsters from your hand or face-up in your Extra Deck to the field as long as their Level fits the Scale created by two Pendulum Monsters. Specifically, that’s all of the Levels between the two end points of the Pendulums currently in play.

A Synchro Summon (シンクロ 召 しょう 喚 かん Shinkuro Shōkan; usually abbreviated Ｓ シンクロ 召 しょう 喚 かん since Duelist Alliance) is the act of Special Summoning a Synchro Monster from the Extra Deck using a Tuner monster with additional non-Tuner monsters.

A Synchro Summon is the act of Special Summoning a Synchro Monster from the Extra Deck using a Tuner monster with additional non-Tuner monsters. In the anime, many characters have chants for some of their Synchro Monsters, which they recite while Synchro Summoning them.

During the Main Phase 1 or 2, the turn player can Synchro Summon a Synchro Monster from the Extra Deck by sending monsters they control to the Graveyard (at least 1 Tuner and 1 or more non-Tuner monsters), provided the total Level of those monsters matches exactly the Level of that Synchro Monster.

Like other Extra Deck monsters, if a Synchro Monster is not Synchro Summoned first, it cannot be Special Summoned from the Graveyard or while banished (unless it specifies another way to properly Special Summon it, in which case it must first be Summoned that way).

Synchro Monsters are like Fusion Monsters. Once the Synchro Monster is properly Synchro Summoned, it can be Special Summoned with ” Monster Reborn “, ” Premature Burial “, etc. as long as the Synchro Monster is not returned to the Extra Deck.