Check do they have organic buyers in their telegram group
No such method to check. Telegram groups are filled with >50% bots and getting inorganic traffic is easy by paying people to add such fake accounts. Social media buzz is never a method to check legitimacy of a project in fact it is the opposite but there is no way to check who is a real investor and who is not. Everyone is free to join a group.
who are their partners
Partners are nothing but names who have some stakes, they are going to sell one fine day before you know it and never come back. They are in it for the money and the promotions. They dont really care about the retail investors.
and where they are going to list their token
Wrong, because a project on a low spending budget would not be listed on a big exchange at first because of lack of trading volume. Next a project which is going as IEO would be already listed but again that does not mean it is legitimate. The exchange gets paid for listing and that is what they want. If the project turns out to be scam, the exchange might delist them and close cooperation - they are not going to be responsible for the losses incurred of other people.
And check the activity of their telegram group
Wrong, read what I wrote above.