Maybe Gem-Knights? They can be played a lot of different ways, so it's pretty simple to learn and agree on something.
One of my favorite combos in particular is to fuse Gem-Knight Obsidian with Volcanic Shell to get out Citrine. Use Obsidian's effect to special summon a Gem-Knight Amber, or any Gem-Knight that it can target. Pay 500 to get another Shell, banish Obsidian to get Gem-Knight Fusion back. If you got Amber with Obsidian, you can normal summon it again (It's a Gemini monster) and use its effect, discarding a Normal Gem-Knight to get Obsidian back to your hand. Use Gem-Knight Fusion, fusing the Obsidian and the 2nd Shell for another Citrine, then special summon a Normal Gem-Knight. Pay 500 LP for the 3rd Shell. Banish Obsidian to get Gem-Knight Fusion back to your hand. Activate it, fusing Amber and Shell into the 3rd Citrine.
Then proceed to Xyz the three into Number 7: Lucky Straight