I will use a 2sc9013 transistor to design a Li-Po battery charging circuit. But, this transistor is not available on my design software. What can I use instead of this transistor?
It seems that the 2SC9013:
is just the same part as the Fairchild SS9013:
The first datasheet also has the same typo (potable→portable)!!! So you can use the SS9013 not only in your EDA software but also in your design, if it turns out to be more available.
As for the simulation part: LTspice has a built-in model for SS9013. I've seen that EasyEDA can import LTspice files, so you could try to either use LTspice and then import the schematic into your EDA software, or directly simulate your circuit in LTspice.
Anyway, this is the model card LTspice uses for the simulation:
.model ss9013 npn + is=3.40675e-14 bf=166 vaf=67 ikf=1.164 ise=12.37f + ne=2 br=15.17 var=40.84 ikr=0.261352 isc=1.905f + nc=1.066 rb=63.2 irb=5.62u rbm=22.1 + re=0.02 rc=0.7426 cje=3.53e-11 vje=0.808 mje=0.372 + cjc=1.74e-11 vjc=0.614 mjc=0.388 xcjc=0.349 + xtb=1.4025 eg=1.0999 xti=3 fc=0.5 + Vceo=20 Icrating=0.5 mfg=Fairchild
If EasyEDA supports standard SPICE syntax, you could create a new NPN BJT specifying that as its model card.