Oracle 23c

BANNER	BANNER_FULL	BANNER_LEGACY	CON_ID
Oracle Database 23c Free, Release 23.0.0.0.0 - Developer-Release	Oracle Database 23c Free, Release 23.0.0.0.0 - Developer-Release Version 23.2.0.0.0	Oracle Database 23c Free, Release 23.0.0.0.0 - Developer-Release	0

create table mytable (region, role, employees) as
select 'Africa', 'Analyst', 2 from dual union all
select 'Africa', 'S. Analyst', 3 from dual union all
select 'Africa', 'Manager', 9 from dual union all
select 'India', 'Partner', 2 from dual union all
select 'India', 'S. Manager', 7 from dual union all
select 'India', 'S.Analyst', 10 from dual union all
select 'USA', 'Analyst', 1 from dual union all
select 'USA', 'S. Analyst', 2 from dual union all
select 'USA', 'Partner', 2 from dual union all
select 'Europe', 'A. Worker', 1 from dual union all
select 'Europe', 'B. Worker', 2 from dual union all
select 'Europe', 'C. Worker', 3 from dual union all
select 'Europe', 'D. Worker', 4 from dual union all
select 'Europe', 'E. Worker', 5 from dual union all
select 'Europe', 'F. Worker', 6 from dual union all
select 'Europe', 'G. Worker', 7 from dual union all
select 'China', 'A. Worker', 1 from dual union all
select 'China', 'B. Worker', 1 from dual union all
select 'China', 'C. Worker', 5 from dual union all
select 'China', 'D. Worker', 5 from dual;

20 rows affected

with
  data (id, region, role, employees, rn) as
  (
    select
      row_number() over (order by region, role, employees),
      region, role, employees,
      row_number() over (partition by region order by employees, role)
    from mytable
  ),
  combinations (region, ids, employees) as
  (
    select region, cast('#' || id || '#' as varchar2(400 byte)), employees
    from data
    where rn = 1
    union all
    select 
      g.region,
      case when g.employees >= 6 
          then g.ids || ';#' || d.id || '#'
          else g.ids || d.id || '#'
      end,
      case when g.employees >= 6 
           then d.employees
           else d.employees + g.employees
      end
    from combinations g
    join data d on d.region = g.region
               and g.ids not like '%#' || d.id || '#%'
  ),
  best_combinations (region, ids, employees) as
  (
    select region, ids, employees
    from combinations
    order by rank() over (partition by region -- per region
                          order by regexp_count(ids, '\d') desc, -- all IDs in combinations
                                   case when employees >= 6 then 1 else 2 end, -- no incomplete combinations left if possible 
                                   regexp_count(ids, ';') desc, -- as many combinations as possible
                                   ids) -- in order to pick only one row per region in case of ties
    fetch first row with ties
  ),
  final_groups(region, ids, rest) as
  (
    select region, regexp_substr(ids, '^[^;]+'), regexp_substr(ids, ';(.*$)', 1, 1, 'i', 1)
    from best_combinations
    union all
    select region, regexp_substr(rest, '^[^;]+'), regexp_substr(rest, ';(.*$)', 1, 1, 'i', 1)
    from final_groups
    where rest is not null
  )
select 
  bgs.region,
  listagg(d.role, ', ') within group (order by d.role) as roles,
  sum(d.employees) as employees
from data d
join final_groups bgs on bgs.ids like '%#' || d.id || '#%'
group by bgs.region, bgs.ids
order by bgs.region, bgs.ids;

REGION	ROLES	EMPLOYEES
Africa	Analyst, Manager, S. Analyst	14
China	A. Worker, C. Worker	6
China	B. Worker, D. Worker	6
Europe	B. Worker, E. Worker	7
Europe	F. Worker	6
Europe	G. Worker	7
Europe	A. Worker, C. Worker, D. Worker	8
India	Partner, S. Manager	9
India	S.Analyst	10
USA	Analyst, Partner, S. Analyst	5