Two questions

How do I upgrade animals i have a rare (1) lvl 15 dune rider a rare (1) lvl 1 stealth worm and a rare (1) lvl 1 blaze camel i want to fuse into the blaze camel because I like the design but the upgrade stats say it will suck despite the lvl 15 dune rider and it being a rare (2) also what are the best effects i should look out for regen anti regen etc