Although I know they get a lot more unique than that
Rare Holo Rare Holo cards feature the same black star symbol as regular rares but with a shiny, reflective foil covering the entire background of the card, except for the Pokmons illustration
Dual-Colored Dyadrine, Synthesis Amalgum (Green/White
Take this recent Red deck, from before the upcoming rotation: Red Aggro - Core Set 2020 Standard | Niedzwiedz, 5-0 Standard League Creatures (22) 3 Goblin Chainwhirler 3 Rampaging Ferocidon 4 Fanatical Firebrand 4 Ghitu Lavarunner 4 Scorch Spitter 4 Viashino Pyromancer Instants (12) 4 Lightning Strike 4 Shock 4 Wizard's Lightning Sorceries (8) 4 Light Up the Stage 4 Skewer the Critics Lands (18) 18 Mountain Sideboard (15) 1 Goblin Chainwhirler 1 Rampaging Ferocidon 2 Fry 4 Lava Coil 4 Leyline of Combustion 3 Risk Factor A deck like this might be built to include a splash of a color to support a sideboard card
If youre set on using Gruul colors to live your Voltron dreams, then Id advise you to roll with a commander that has gone a little out of fashion recently: Uril, the Miststalker
Koma, World-Eater $6.47 Koma, World-Eater is the kind of card thats great for introducing players to the idea of building around one big threat