Domination, Crazy King, Chaos Ball, that other Chaos ball where you transform into a beast
All of these involve movement around the map, or whose objective has a limited duration (and in the case of the chaos ball variants, healing is diminished with the ramping damage).
Generally speaking though, modes where sticking in a stack is somewhat detrimental compared to the ability to secure objectives. (two 4 stacks can capture more objectives more quickly than a single 8 stack, or one 4man can impede the 8 stack while the other 4man captures objectives).
That is not Deathmatch.
That's just ballgroup gameplay.
It's a pain.
(I'd also suggest making the polymorph chaosball the standard one, as it seemingly reduces a teams effectiveness the more objectives they hold at once via the limiting of abilities).