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Several of those aren't functional triangles, since one of the types is immune or non resistant to the other.
Grass doesn't resist Rock and Rock doesn't resist Bug, but Bug resists Grass. Ground's immune to Electric but Water deals neutral damage to Electric and Water doesn't resist Ground. Dark's immune to Psychic, not resistant. Ice doesn't resist Ground. Ground doesn't resist Steel.
Grass/Ground/Poison works, and so does FIghting/Flying/Rock... but I'd sooner choose between Grass/Water/Fire than Grass/Ground/Poison or Fighting/Flying/Rock, personally.
There's a reason why the starters are Grass-Fire-Water beyond the fact that it's a functional triangle. The strengths and weaknesses of those types in relation to each other are intuitive: it's obvious why Fire would be weak to water, while it's less obvious that, say, Fighting would be weak to Flying, or Psychic would be weak to Ghost.