They're 3 3-tile support characters that are for the most part banned from online play (Not officially, as far as I know, but it's discouraged that you use them), I never remember the other 2, but yea Trunks is one because he auto-starts and can even be started in the air.
You forgot to mention that the Seiya support is also rigged because it's tough to impossible to counter it since it's summoned from the top where as other supports have a delay time which they are vulnerable for one to counter it.
Trunks is also useful for blocking support komas. For example Hibari's grab where he grabs you and carries you to the corner. Trunks can get you out of that. I think its the same with Rukia's jumping grab, trunks can get you out of that.
in my opinion sena 3 is the cheapest coma since you almost CANT block it.
and if u can you dont have enough time to block the opponents next attack.
example:use sena 3 charge a special move that guard breaks= near 100dmg depending on specials.
the easiest to block should be seiya, since it has a delay and even if you cant block it, its only 22dmg max.
but seiya is very good at blocking other support comas that comes after you.
trunks is very cheap and can destroy you if you aren't careful for combos.
and sena is cheapest since a mass sena 3 can destroy your soul-bar and you cant do anything.
The bad part of this is when a cheater uses, because only use trunks, trunks, trunks ever and you cannot atack...., If the game makers fix this for the next Jump game (maybe it comes never...) Will be pretty that the 6 koma dio ability and big 3 ones have now a weak point.... or just remove...
I have the same one in my other 3 switches. it's never had a problem with about 10GBs of space left. I'm going to check it when I get it so it may be Wednesday before I start downloading games on the oled.