Fusamatrix

It gives you a ramdom combination of the two aliens you select (ex: if you select heatblast and upgrade and then try the same thing again you might end with completely different aliens or very similar aliens)

contains all aliens from the omnitrix and ultimatrix, and then some

select two aliens on the sepate faceplates and press them both down

you can also just select just one alien by just using one faceplate

you can evolve fused aliens

you can also fuse evolved aliens