Understood, samurai are not plentiful in just RW. So you would need shapeshifters or to splash a color to have enough decent samurai for a deck.

For typal strategies humans, soldiers, warriors, and artifact creatures are all very well supported

RW is rather limited in what it can do. The bigger question is how competitive do you want to be?
RW typically does: modified creatures (equipment/auras), Burn, Lifegain, spellslinger, tokens.

If you want to do samurai typal strategy I would suggest Isshin in RWB so you can double attack triggers