How to teambuild around a offensive fire-water-grass core?

Question

So I hear a lot of experienced people saying "if you already got two of them just complete the triangle". I have a band meowscarada, a specs greninja and a scarf cinderace, and I wanna teambuild around it.
NOTE: I don't want a specific Pokemon - just say "an intimidate Pokemon" or something else.

EDIT: so I scrolled through all the formats and I don't know which one to choose, but I think VGC Reg set I is my one, so yeah whatever's different with this format I hope could give you some clarity.
(also someone explain what VGC Reg set I is please?)

Comments

The answer's going to be different for different formats. Cores that need to prepare for Calyrex are very different from cores that don't. Are you sure you don't want to just pick a popular format and ask about that?

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“I’m not a fan of formats”. Umm what? Every battle is in a format. I am confused. Extremely utterly bewildered

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I mean in particular, I don't want "your team can be easily countered by this and this!" I want "you need bulky pokemon, more protect users" - in general I don't want my team to revolve countering a common threat.

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Ok.          .

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Countering common threats is how you win games. Do you not want to win games?

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The reason why giving advice in isolation without appealing to specific Pokemon (on your team or opponents') is difficult is because the answer is always going to be "it depends". It's like asking, "What should I wear today?" with no information on what the local climate is like or what activity you're doing. Well, are you going swimming or is it -40 degrees out? A good choice in one situation can be really bad in a different context... The other way to respond is just saying "Wear what you like, wahoo!" but that's not super helpful and might cause you to walk into a blizzard in shorts. It's ok if you don't want to be super serious about competitive Pokemon, but people are just trying to be honest that you'll have a tough time winning if you're playing on a platform like Showdown!.
That being said, you might enjoy these answers. They are old, and they do mention specific Pokemon, but I think it's the closest you'll find to a "general advice" type answer. I left some Smogon articles on your other question and although Smogon will generally be VERY particular about the nuances of formats, you can read their resources to follow along with their general process in building a team by looking at the reasoning in why they picked certain Pokemon.
https://pokemondb.net/pokebase/251737/what-does-a-balanced-team-consist-of
https://pokemondb.net/pokebase/245834/what-would-be-an-ideal-number-of-each-role-to-have