If you have the anti damage program..install it into megaman...it really helps you to counter those powerful attacks of bass but i would recommend staying in the back while trying to counter. Of course..you need strong chips and have at least one giga chip in there too..(whichever you are most comfortable with..there are many)

Put a RiskyHoney 3 A or D, Dblpoint * and Atk+30 * while in focus or angry state or use
TomahawkCross..

I defeated him w/ this strategy in a second!

The chips that beat Bass BX is...

Standard:
Risky Honey 3 M x3
Bubble Shot 3 (any code) x1
Doll Thunder 3 M x1
Life Aura U x1
Sanctuary Z x1
Attack + 30 * x1
Double Point * x1
Recovery 200 Z x2
Recovery 300 J x2
Life Sword(Sword,Wide Sword,Long Sword S x1)
Fast Gauge * x2
Full Custom * x2

Mega:
Roll 3 R x1
SlashManSP S x1
ProtoManSP B x1
SpoutMan * x1
Colonel SP C x1

Giga:
Bass F x1

NPC:
Number Open(Pink)


You will calm the damages of the multiple bullets
by the Sanctary and Life Aura,Sanctuary halves the attack of Bass and Life Aura
deflect all the attacks under 200.The Life Aura can disappear when attacked by Tank Cannon,Hell's Rolling and Gospel Breath.

you dont need too pwrful chips you just need the ground crosss