I have a mak90 with trs 25 mounted to an ultimak rail. What range should I zero my red dot at? Is their anything like the 25/300 meter zero for ar's?
Rifle will primarily be used for range use from 15-200 yards

Put the rear sight on the "1" (100 meters)

Sight in at 25 meters to get on paper... Then 50 meters.. Then 75 meters... All with the sight still on the "1" setting .. You are working out to the 100 meter mark

Then, sight-in @ 100 meters  with the sight still on the "1" setting .. This will give you the full use of your rear sight..

I know I have simplified it much but others will chime in with various methods

irons are almost dead on but im wanting to know about zeroing the red dot I have on it

Depends on where you want it to hit. A 50 yard zero should do you pretty good out to 200 yards.

This. An AK's "1" is almost identical to the "3" mark. This is why they suggest "1" for sighting in. The ark of the 7.62x39 out of a typical 16" AK barrel will yield similar POI at 25m and 300m. If you 25m zero your AK at "1", you will be close at 300m on "3".
If you use this (proper AK sight in), your BZ (rearmost setting below the "1") will be about a 200m zero (good "set it and forget it" battle setting) for overall use (not precision).
Please do NOT zero your AK at 25m using the BZ... your scale will be useless if you do. That's a common mistake. If follow the proper 25m/"1" method, you'll retain approximate use of your scale AND have the BZ setting option (as it was intended).

NO.
The 1 is the setting for 100 meters, the 3 is the setting for 300 meters.
The difference in point of impact at 100 meters is about 10 inches!

The battle sight setting is the same as the 300 meter setting.

With a RDS, I zero at 100 yards and know my hold-overs out to 300.  Good enough for me and my usage.

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Recently did my Saiga with setting for 100m and shot 25m to get on paper and 'tight', then moved to 100m.

Seems good enough for me. nice to have personal 125yd range as well.  :)

I already explained that the 1 and 3 (100m/300m) were very similar (they are not identical). The BZ is not the same as 3, but closer to it than the 2 (I'd guess that the BZ is probably closer to 250m). 1 and 3 are not the same, but 25m/300m are close POI (thus why 1@25m gets you close on the scale). The 25m/"1" sight in is the recommended sight in for AK sights.

A properly zeroed 7.62 caliber AK fired at 100 meter with the sight set a 3 (300 meters) will put its shots 10+ inches above the point of aim. If you believe that's " very similar" you're in a class by yourself.
The truth is that 25 meter zeros are used to "get on the paper" before actually zeroing the weapon at 100 meters by those who can shoot, and are used to approximate a zero by those who can't shoot well enough to get a group at that distance.