For Attack; look for these: Flash Sagittario, Wyvang, Balro(Those two are from the Ultimate Synchrome DX set Defense and Stamina, so you may want to buy two if you can to synchrome them). Assuming Hasbro releases Wyvang and Balro.
So you can create: Flash___ /Wyvang Wyvang GB145/H145/W145(From Samurai Ifraid)/S130(If you have any of those)R2F.
For Defense; look for these: Leviathin, Kiracken, and a Jade Jupiter or Blitz Unicorno/Striker for its rubber defense tip. Leviathin and Kracken can be obtained from the DX set I mentioned above.
So you can create: Kracken/Leviathin(Leviathin on top) BD145CS/RSF/RDF/RB.
For Stamina; look for these: Phantom/Genbull Genbull( Griffin Dragoon 2-pack with SA165,(Only through Hasbro), and an Evil Befall can be useful for EWD. If you are willing, you can purchase a Berserker Behemoth for SR200.
So you can make: Phantom/Leviathin Dragoon(Killerken can also work)SA165WD/EWD or Genbull Genbull SR200TB.
For Balance; look for these: You'd need Genbu, Dragooon, Samurai Ifrit, Diablo(Optional), or 2 Giragos.
So you can make: Genbu Dragooon F230CF, amazing combo; or Diablo Bull/Girago Girago BD145RF/R2F/LRF
Overall: Genbu F230TB, Griffin Dragoon two pack, A Leviathin, and a Samurai Ifrit.
Hope this helped.
Edit: And of course if you need Zero-G combos or Limited Combos; just tell me.
6 God is watching and I hope you're prepared to face him