Equipment potentials AND stats are ignored altogether. You can enter naked and nothing will change.

Your character cards, link skills, inner ability and class' skill passives (including those actives's passives that you don't bring to the battle), your level stats, your arcane symbols and your nodestone boosters still counts and they are your main source of damage increase with Ursus.

Your ATK/MATK is skyrocketed and fixed at 10610 and can only be changed by the sources stated above. This renders fixed ATK/MATK buffs as useless and ATK%/MATK% sightly stronger. Starforce benefits caps at 120 or more and all that starforce does is to set your base ATK/MATK, 10610 is archived with 120+ starforce, but it can be lower with less.

Personally, for Queue Ursus I recommend LV200+, 50+ Arcane Force, LV3+ Skill Boosts, 3+ Link Skills (Damage related), 120+ Star Force. In that way you can always rank up mesos. With less you can still rank up, but you will fail to do so often, too, though some classes might still be able to nail it consistently. For 6-Party Ursus, LV170+, 120+ Star Force and 2+ Link Skills are often enough to rank up mesos, but only if the party can deal a good damage.