Slow teamers dominate agar.io 9 months since the anti-teaming update. It's the current teaming problem in FFA and Experimental; a highly illegal activity. This teaming technique contravenes the anti-teaming measure, the feature that prevents teaming which contravenes the merge-time after splitting. FFA means Free for all, opposite of teaming, and teaming in Team mode isn't identical to the illegal teaming in FFA and cross-teaming in Team mode, which is prevented by anti-teaming.
If you encounter one
Just maneuver around the slow teamer and if it doesn't avoid a virus or a spawner and suffer nothing when eaaten, the cell is split in 16 and won't split-kill you. Keep maneuverng until you find thew smaller cell. Now occasionally the smaller cell will eat the small pieces of the big teammate and kill any big cells trapped near it. And again the big cell will split in 16 again and take out any cells and viruses in its wake and turn into a bait again
While it's in 1 piece
Stay away from the teamer because it'll eat you when it becomes ready to split in 16. The safest way is to hide behind the teammate unless it's in one piece when it trigger the 16 split. This is a technique espcially if you're less thqan 6 times smaller than the big teammate, but be aware that the smaller teammate can split to eat smaller cells.
Viruses aren't worthy on the small because it'll trigger the split-to-16 interaction, but if it's shot on the big teammate, the sghrapnel could eat you, the team may transfer mass to the small teammate, but if you're lucky enough, you could eat small virus shrapnel, but always move away because the smaller teammate will help the larger teammate to eat you or transfer mass to the smaller teammate.
When it splits in 16
Make sure you're split in 2 before the teammate and stay away from 6 splitting ranges. The pushing distance increases the split distance and could be fatal. If you're large enough, make sure the small cell doesn't eat you when it splits.
Also make sure you're not trapped between many cells because the cells can rush straight towards it with the cellular forces
While it is in 16 pieces
If you're big enough, try defeating the smaller teammate. This is where viruses work best. Virus the smaller teammate, but make sure it doesn't quickly cause the big teammate in 16 to transfer its mass. If you can't defeat it, move away unless you or the teammate are both split and the timing is right. The teammate merging could trigger the return. Make sure one of ypur peces get eaten by the small cell and merge-kill its small pieces before the teammate can eat the small cells.
Don't virus the big teammate, because the teammate won't explode if it gets virused. The teammate will also be invincible to anti-teaming that way.
When it becomes ready merge or transfer mass back
Make sure you're not buried in the cell because the teammate will eat you when it becomes ready to transfer and make sure you're not too close and you're big because the cell can eat you. Just stay close to the small teammate, not in the way when it gets big. Move away and wait for it to split in 16, split while the small teammate is in 1 piece and merge its small teammate while in 16.
If you managed to defeat the slow teamer, you could get 8000 to 40k mass but the game will lag due to the extreme FOV.