Gogeto

The fusion taken place when Gogeta adds the potara earings on himself which creates a fusion between Vegito and Gogeta which adds ultimate power.

Gogeta changes clothing during this transformation, he keeps his top half of clothing but gains vegito's lower half (vegito's bottoms and shoes).

The estimated power level of Gogeto is an outstanding 8,700,000 (compared to gogeta's 2,800,000 during the fight with Goran).

Fusion
Gogeta starts glowing and a flash of light occurs before changing. Gogeto has the power to transform into Super Saiyan god when needed as Goku transformed into God before and Gogeto has enough power to gain this transformation without a group of pure hearted saiyans.

Gogeto when in god mode is the most powerful being in the universe until later encounter with Android X.

Android X
Android X is the ultimate creation by Dr. Gero. It is a mix of all androids together including Cell, Android 13, etc and with updated saiyan features. Android X was sent to gather knowledge from the universe to use it to kill Goku. Android X learnt abilities such as: Instant Transmission, Super Saiyan (Android/Saiyan DNA).

Goku encounters Android X in west city during a major attack on the palace. Android X taunts Goku and attacks him. Goku has no chance of fighting back as the android defeats Goku in a matter of seconds. Gohan appears and fights Android X but suffers the same fate as Goku. Finally Vegeta arrives and fights with Android X and manages to knock him into a few buildings.

Goku and Vegeta manages to fuse before Android X returns. Gogeta starts fighting with the android, still not having a chance against him but later is thrown the potara earings and is told to put them on to transform further.

Gogeta places them and turns into Gogeto but Android X transforms into Super Saiyan and fights an even battle with Gogeto until Gogeta turns god mode and starts winning against the android.

Furious with Gogeto's abilities, The android transforms further into Ultimate mode where he ends up destroying the potara earings and Gogeta turns back to Goku and Vegeta.

Goku, Vegeta and Gohan end up killing Android X with an Ultimate Big Bang Kamehameha.