Might be a bit of repeating what Argothair said but here’s my take for zany plays.
Fair warning: none of these are “viable” but they should definitely spice things up:
USSR: Charge the starting FTRs into the Baltic to interfere with Germany’s opening (even if you have two and it’s a terrible odds battle).
Turn the entire Allied effort into a game to see how long you can keep Karelia alive. Fall back when you need to so you don’t get your stack wiped out.
Alternatively, build a tons of tanks and try to kick Japan off mainland Asia at the detriment of the German front.
Germany: Build an Aircraft Carrier or two and a few Transports and dominate Africa/the Baltic/the Atlantic.
UK: Play in the Atlantic. Funnel 1 FTR a turn to Moscow to help their defense.
USA: Do something totally out of left field like an IC in Alaska. Alternatively, build 1-2 Carriers in the Atlantic and fly FTRs to UK.
UK+USA FTR Conga Line:
1. Build 1 CV off US East Coast (don’t have the board with me so I don’t recall the exact Sea Zones, sorry).
2. Build 2 CV + supporting fleet (DDs mostly) off UK (SZ that’s next to the Baltic Sea).
3. Example turn:
a. Start with 2 CV, 2 UK FTRs, 2 USA FTRs, other supporting vessels in UK SZ. Start with 1 CV, 2 US FTR in US East Coast.
b. UK Turn: Move 2 FTRs from UK SZ -> Baltic SZ -> Karelia -> W. Russia -> Moscow, build 2 new FTRs to replace the old ones.
c. US Turn: Move 2 FTRs from US SZ -> Atlantic -> Africa -> English Channel -> UK SZ, move 2 FTRs from UK SZ -> Baltic SZ -> Karelia -> W. Russia -> Moscow, build 2 new FTRs to replace the old ones.
This essentially dumps 4 new FTRs in the USSR each turn (you can do less/more if you want), which is 40 IPC of income. You can use your FTR fleet to wipe smaller stacks to make trading more bearable for the Soviets.
Hope these ideas help somewhat, even if they’re not the most competitively sound strategies!