>>53338532Even non-EX’d free and pool units should be able to beat vanilla Champion Stadium, so I assume you must be missing something super basic.
Did you set your targeting order as per
>>53338566?
Are you reading the “tips” for each stage and building a team around that?
Are you effectively lining up each stage with an advantageous (or, at worst, not-disadvantageous) round bonus?
Are you blowing your wad too early with your strongest units and running out of stuff to use for later stages?
It can be helpful to plan everything in advance so you know what order you want to challenge the stages in, and what team you plan on bringing, before you start a single battle.
The basic strategy, assuming you have EX supports, is to sync with your support first, then sync with your tech or striker. If you aren’t yet at the power level that you can clear before or 2-3 turns after the first opponent sync, then having a healer is mandatory because the opponents hit much harder post-sync.