USPD and KPD "Independent Social Democrats" (smaller Marxist groups) and Communists - 62, 45, 54, 77, 89, 100
SPD - Social Democrats - 100, 131, 153, 143, 132, 121
DDP/DSP - German Democratic Party / G. State P. (1930-) - 28, 32, 25, 20, 4, 2
Zentrum - Centre (Catholics) - 65, 69, 62, 68, 75, 70
BVP - Bavarian people's party (regional Catholics) - 16, 19, 16, 19, 22, 20
DVP - German People's Party (liberals, Streseman) - 45, 51, 45, 30, 7, 11
DNVP - Germ. Nat'l People's Party (nationalistic, former conservative party) - 95, 103, 73, 41, 37, 52
NSDAP - National Socialists (Nazis) - 32, 14, 12, 107, 230, 196
smaller parties - 29, 29, 51, 72, 11, 12
total - 472, 493, 491, 577, 608, 584
Center party headed the goverments 1923-4 and 1926-8 under Wilhelm Marx, and 1930-1932 under Heinrich Brunning. It was in fact the party most frequently in power in the Weimar Republic. The BVP were their regional allies and essentially a branch of the center party.
SPD headed the government 1928-1930 under Hermann Muller. The 1924-5 government was headed by Hans Luther, an independent of the center-right, who governed with support of the DVNP and DVP. Streseman of the DVP held the foreign ministry from 1924 to 1929.
The center of the political spectrum was the center party, that is why it ran governments. The economic liberals dominated foreign policy but not domestic, through Streseman and before him Rathenau. The middle ground was that occupied by the SPD&DDP on the left, and Center, DVP, and DNVP in that order on the right.
In 1932, von Pappen and then von Schleicher headed governments of the old right. von Pappen was the party candidate while Schleicher was favored by the army. It was von Pappen who invited Hitler to joint the right in government, trying to regain his own position after being dumped for Schleicher and thinking they could "handle" Hitler.
Economically, the center party was in favor of wage and price controls and supported trade unionism. The first differentiated them from economic liberals, the second from economic conservatives of the old right. All the conservative parties added "people" to their names and dropped conservative; the term had sufficient nationalist appeal to make clear who was who. Adding "national" denoted a party of the right - all of the left wing parties were international, and the liberals were free traders committed to good relations with the west.
Meanwhile, Christian did not connote non-socialist - there was a Christian Socialist party and the Center parties "sold" their unions and price controls policy mix as a traditionalist and Christian form of socialism.
The experience of WW I is what broke the link between anti-socialism and the right's main marker, which was nationalism. The hard right after the war had seen war economy measures and thought them a solution to the left's social justice concerns, that were compatible with nationalist devotion to a common cause and with militarism.
What was considered "reactionary" was combining nationalism with support for capitalism, which was passe - the new right kept the nationalism and put war mobilization of the economy in place of capitalism as economic policy. This was justified as less "selfish". We see the same attitude contagion among protectionists today - starting from patriotism they notice that markets are not exclusive and loyal and steadily seek to replace them with some political arrangement that seems to be, instead. Mussolini pioneered this approach, changing from a simple socialist of the left prewar to a strident nationalist after WW I.
The Nazis governed with the support of the right, entering through a deal with von Pappen. They had only 3 positions in their first cabinet. There isn't a leftist in that cabinet. The right brought them in, hoping to use them to fend off the left and destroy the communists in the middle of the depression.
The old right had just thrown out the Center party leader Brunning for two of their own (with plenty of infighting between them, party leaders vs. scheming generals, etc) - because Brunning had ruled by decree without a majority and his combination of balanced budgets, deflation, trying to get out of reparations payments, and wage and price controls, had utterly failed.
The left right cleavage ran internationalist - nationalist, not pro capitalist anti capitalist. All the pro capitalists combined wouldn't fit in a teacup. The traditionalist right did not base its claims to superior social positions on wealth, but on nobility, national service, and the army - they claimed to be bigger patriots more willing to give their lives for their country, not to represent the rich. The latter they treated as a left wing slander.
Communists - nationalize all major industry. Repudiate all foreign debts. Align with Russia against the capitalism west.
Social Democrats - nationalize some industries, progessive taxation and welfare transfers. Pay reparations, keep alliance with the west, but willing to weaken currency or repudiate commercial debts.
Centre - leave industry private. Wage and price controls instead. Deflate, strong currency. Negotiate end of reparations. Keep alliance with west.
Liberals - leave industry private. Free market wages and prices. Pay all foreign debts including reparations. Keep alliance with west.
Germ. Nat'l People's Party - Industry private, prices uncontrolled, oppose unions. Willing to repudiate foreign debts including reparations. No inflation of the currency. Protection. Go it alone in foreign policy.
Nazis - Industry private but state budget vastly increased, inflationary finance OK. Foreign exchange controls. Repudiate foreign debts. National service acts.
All in a context in which the economy faced crippling foreign obligations, the banking system had collapsed trying to maintain a fixed currency peg, western capitalist states insisted on full repayment in gold in the middle of a world wide depression, and unemployment was 20%. The hottest question of the day was, who is to blame for this economic disaster and who do we murder to get ourselves out of it? The left said kill your boss, the right said its them damn foreigners. The free market liberals said "pay up" - and got about 7 votes.