Post-Marius legion looks like this:
Roman core: 1 General, 1 Aquilia Cohort, 9 Legionary Cohorts, 1 Equites and/or 1 General (youth)
Deployed thus:

You lose all the Italian troops, I believe, with the Marian reform event (though Italian troops didn't
actually disappear until some time after the law giving citizenship to all Italians who didn't fight Rome
in the Social Wars, in 88BC). This means you have to rely on AoR troops and mercenaries for your
auxilia.
Again a fairly equal number of them to your Romans (though sometimes there were many more). Get a
couple of units of local cavalry, 2-4 units of skirmishers and make up the rest with line troops to cover
your flanks.