how much ARM and MOTO you make for barbarossa? Single player and Multiplayer...
How About Shore Defence? Do you use garrison units (how many in one place)? and do you use own troops at france shore or ally troops?
There isn't a 'correct' number for either ARM, MOT, or coastal defenses.
Coastal vs. AI - what TK3600 said, or, if you don't have a navy, 1/2 GAR + a few mobile divisions who can move/strat redeploy to the spot in question.
Coastal vs. Human - You can't assume you'll be able to do what TK3600 said against a decent human player, because such a player won't waste his troops unless they have a good chance of guaranteeing at least local naval superiority.
In that case, you'd need
--2/3 GAR on all beach provinces
--1 GAR on all non-beach provinces with a port
--1 GAR on nearby airfields.
--sizable mobile reserves - enough to prevent a beachhead + have additional reserves for additional invasion points.
--sufficient AA/INT/FTR to prevent many sorties from his bombers.
--a few V-1s/V-2s, which are OP at destroying infra. In case he lands, you should force minimal org regain until you can bring enough troops to close the breachhead.