Tuner Synchro Monster

Tuner Synchro Monsters are simply Synchro Monsters that are also listed as Tuners, similar to Monsters that are Toon, Union or other secondary "Arch-Types". While cards of this type (as in having Tuner printed on them) were introduced in "Starstrike Blast," it was already possible to simply make/treat Synchro Monsters as Tuners (such as with Lightwave Tuning or Psychic Tuning). Tuner Synchros in particular however are required for a new method of Synchro Summoning called "Accel Synchro", which is used to bring out the namesake "Accel Synchros" (which will accept any Tuner Synchro, whether it was a "printed" or "altered" monster). Otherwise, these are still simply both Synchro Monsters and Tuner Monsters with all the rules and conditions that normally apply to both respective types of Monsters.

That said, in the OCG/TCG, (printed) Tuner Synchros, except Life Stream Dragon, also have an additional condition allowing the player to conduct a Synchro Summon during their opponent's Main Phase as long as they are used as one of the Synchro Material Monsters. In the anime, this condition was actually part of the Accel Synchro Monsters themselves, but with this change in the real life version, it downgrades them to normal Synchros with restrictions and upgrades any Synchro that would use a (printed) Tuner Synchro into having the same effect that was originally reserved for Accel Synchros.

These cards are currently the only Tuner Synchro Monsters in OCG/TCG cards so far: