You exceeded the maximum number of trainings some of the trainings will not be imported - epix gen 2 , why?

Storage does not matter. Garmin has a hardcoded limit in the software. Do what the watch is telling you. Delete some trainings. 
Same is for courses. Hardcoded limit. 

How i delete it?

May be ita because i m using Garmin explore app?

Delete them directly on the watch. Open activity, select the training, delete the training. 

It is just one of obolete and unnecesary software limitations. For watches with large storage, it makes no sense.

Users have requested that to change for a while now, but it remained the same.

So, there is no workaround - deleting unused trainings from watch is thr only option, as above mentioned.

Limited to 25 across all activities - not sure why - but maybe a hardware limitation from processing perspective (maybe for older watches - maybe if asked garmin they may respond). This includes any that the watch came with i.e. yoga/breathing etc.

If on Beta there is now the workout section which makes this super easy.

Another way to get around this limit is to only save your regular daily workouts - for the others (occasional / one off etc) then use the calendar for these i.e. don't sync to the watch - just sync them to the calendar on the day you want to action them - then when go to do the activity, then just pick up from the calendar i.e. on latest version of connect app (android but should be the same as iPhone due to latest update) - press more (bottom right) - training & plans - workouts - select one or find one  - save to workouts. Click on workout so have send to phone option - but instead of using the send to phone icon (top right) use the 3 vertical dots to the right of send to phone and select add to calendar. then sync app with watch. 

Only bummer is if want to sync multiple days no option for this other than to go through the add to calendar option each time.

Once synced (if current day should show on MyDay feed) or if future day should be able to see it on the calendar for that day.

On the watch to select the activity: If its the current day can click on calendar in watch (if have date/calendar data field long press on them - should show up under current day  (may have to scroll up as usually set at 00:01am (yes would be nice if we could set the time too), and press on the calendar event - will take option to do workout, view the steps or to edit it (will open app) - if select do will take you right into the activity and all you need to do is press start (best option if custom workout as will offer you to select the activity you want to use). If want to action via activity, then select activity (i.e. if run workout then select run) - if set to today will auto come up, otherwise need to go menu - training - and select calendar.

If on beta - have 3rd option - the new My Workouts - make sure its set as part of your activity list -then select My Workouts. Top will have total workouts that you created that are loaded onto the watch (i.e. part of 25 limit) - scheduled will show any calendar ones - the individual activity types will then list the ones you created plus the ones that came with the watch (these all go to the 25 limit - so a good way to find these and delete them). Blue dots just notifiy new ones you haven't seen  - once gone through then gone out, if you come back in blue dot will be gone.Can delete by going into the workout, or action it or edit (which will launch the app).

jaamgans said:

Limited to 25 across all activities

As noted this has been around for a long while. In a way it makes sense. What should be the limit, 100, 200, no limit? With too many custom workouts on the watch comes the problem of finding the one you want. Imagine having to sort through them just before you started an activity. The new Workout app does some sorting for you but the best place to keep large numbers of custom workouts is surely in GC.

Vizi said:

there is no workaround

The suggested workflow, and one that has been suggested on most occasions this topic comes up is as detailed above. Keep the majority of custom workouts on GC and schedule them through the Calendar to your watch. Keep some of the ones you use most frequently on the watch up to the limit, and now utilize the new workout app to quickly find them. 

Vizi said:

oes not mean that it is a workaround. Workaround is a bypass of the problem - in this case there is no bypass but users have to accomodate exactly according to implemented (and noncensical!) limitations.

Actually the definition of a workaround is: a method for overcoming a problem or limitation in a program or system

By scheduling to the calendar you do overcome the problem/limitation of the program or system as you are still able to use that workout - its technically on the watch and available for use - hence you have overcome the problem.

Agreed it is a permanent solution - its temporary as if its a a workout you use semi-regularly that can be an issue.

But TBH - would be surprised if you need more than 25 regular every day workouts.

But also agree that with the new workout activity it would be nice if the limit could at least be doubled for those who do want more, if it didn't impact performance.

This just does't make any sense. My coach schedules my monthly training plan on TrainingPeaks. So yeah, probably more than 25 workouts. 
Just frustrating having to deal with this almost daily. EVEN WORSE, starting an activity and realize there's nothing in the calendar for the day! Crazy!!

My workaround is that I have set up a few „standard“ workouts for my use cases which I edit the day I am about to do a workout.

e.g. I have a workout called „hill sprints“ that has the basic structure with warm up, sprint section, and cool down, and it takes me about 1 minute to adjust preset times, # of intervals, distances and to sync to the watch.

likewise for HIIT I have stuff like AMRAP12 with an established structure for warm-up and cool-down where I only have to replace the exercises and # of reps for the main workout. 

after getting over my annoyance with the unnecessary small limit for workouts on the watch (I totally agree that this feels like a problem from the 1990s) this has actually improved user experience for me. Because adjusting the workout takes mere seconds. However, I am typically only planning my workouts zero to two days in advance and don’t have to pre-program 25 workouts.