Let's talk about the Arena.

Arena.

1. Once you have reached the levels 500, 1000, 1500, 2000 and 2500 you cannot sink lower again by getting attacked by others. This does NOT count for lvl 3000!   This opens opportunities for cooperation.

2. When battling up, you need to reach a level, 200 below the next level, to see the players above you. So you need to reach 1800 to see the players at 2000. 

So when somebody of your guild reaches 2000 and he lowers his DEFENSE (not same as attack team)  to 1 weak hero, everybody else can attack him  - getting fast raises - to also get to 2000 while the attacked person stays at 2000.  (this also gives much coins for the shop)

On the other side: you see a fellow guildmember at 1750. He cannot see you until he reaches 1800. So you can help him by attacking him ...  and LOOSE your fight. To be sure that you loose, attack with a single weak hero. HE will get the points. Lift him up to 1800 and he can refresh and attack you. 

example, look this picture:

You see, I loose nothing.  I am at lvl 2000.  I levelled Ventt to 1800 and told him to attack me.  I levelled Hikimori to 2300 and told him to refresh and attack fellow guildmembers at 2500.

Ultimate Champions 

This is a different story. You are not pinned at levels here. This is what I do because the reward in the end does not make that a big difference that I want to end up high.

I play here ALWAYS with only 1 low hero defending. I pick my fights, attacking somebody with the highest difference in points between me and him because that gives more reward in coins for the shop. After my last fight, I refresh. Next day you will be back to 0! :-)  BUT with players with high value in your list to attack. Every attack now gives a big reward in wrestle coins! Start with the lowest one, so you can attack as much as possible. The result is that you can buy much in the shop! That is more worth to me then ending up high in the ranking.

Should you want to end up high in the ranking, then you just can do that on the last day nevertheless, but then you need to change to a complete defense team of course.