The best core monsters in the main deck tend to be Red Sparrow Summoner, Torapart, Samurai Sword Baron, Assault Dog, Motivating Captain, X Saber Fulhelm.
anoymous
Junk decks can easily Synchro summon level 5 & 6 monsters and they use Earth Tuners. Plus, they got some nice support recently.
Karakuri or Superheavy Samurai could also summon them without problems. But they usually prefer their own Synchros.
Six Sam do also have 2 Earth Tuners (level 1 & 2), so they would work too. But you have to justify using Goyo stuff over Shi En.
Or just use Unexpected Dai + Angel trumpeter + some low level monsters like Quillbolt Hedgehog.
anoymous
Goyos are Extra deck only. You can combine them with literally any deck that can bring out the Synchro Monsters.
So, maybe just use a meta deck and sneak in some EARTH tuners with a suitable level?