3V blue 20 mA LED not working with red/yellow LED(2V 20mA)

I soldered 5-2V red LED's in parallel to a 10 ohm resistor and did the same for 5-2 V 20 mA yellow LED's. Then soldered 5-3V blue LED's together in parallel. When I connect blue and red/yellow to the same 3 V battery(2-1.5 V alkaline batteries) the blue LED's receives very little power and is very dim. I didn't connect the blue LED's to a resistor and it's labelled 3 V 20 mA.

Would the LED's be mislabelled? If i connect the red and yellow LED's to the same battery it both wouldn't dim much. Would it make it maximum brightness if I connect more batteries in parallel?

if you add a slightly different say 9 ohm and a 10 ohm resistor to each LED's would it be significantly dimmer for the one with 10 ohm?

Current flow, voltage sag from the alkalines, the Vfs of the specific LEDs, and the resistances you're adding all interact in to affect the balance of currents going to the different LEDs. It's hard to calculate and it's not surprising that your first approximation does not yield balanced current flows. I'd probablly try to breadboard the whole set up first and adjust the resistances (or use a pot) to make sure I had the balances right before I soldered anything together. Good luck.

The Blue leds require a higher operating voltage vf than the red leds, usually just over 3 volts