[Question/Story] Best way to report a cluster/horde?

Hi travelers,

I premise I hadn't fight gyms from december until the beginning of this week.

Today I was on the seaside, a small city full of X color(I don't want to name teams) gyms but 3 being Y; Z team had none.

I'm from team X, so I went to prestige 2-3 gyms and then I took a look at Y ones: level 10 full-Blissey gyms owned by 10 accounts with similar name, all having the same ABCDE and/or FGHIJ in the name(I won't say the real 5 letters) and all level 37+.

Being X gyms owned by a wide variety of levels(cp 1600-3000) I decided to help beating these "clearly spoofed/botted gyms", just to remove all these Y 2500+ Blissey.

As soon as I began, another X team player came and we teamed to 10->0 one of these Y gyms.

It took about 15 minutes.

As soon as we finished, we took a look at the gyms scene:

the whole city was Y; ~8 level 10 X gyms were beaten and became Y level 10 full-Blissey gyms.

This X team player decided to say nothing about this, to avoid his Telegram group raging to him.

8x 10->0 and back to 10 in about 15 minutes. To do such a thing, you need to win [2x(50x8)=] 800 fights in 15 minutes. Obvisously, none was there(one of the gyms was near us).

Question: how can I acquire prooves to send, about this?

How can I report this cluster/horde of bots/spoofers?

I want to help that guy...I feel guilty for making that cluster mad and ruining everyone's gym experience!

Edit: typo