Ratchet & Clank: Size Matters

The RYNO will be available from the vendor when you enter challenge mode. It will cost you a solid 9.999.000 bolts.

Bolt grind:
The most effective way I've found was a reddit post which recommended to get a 12x multiplier, enter the High Impact Treehouse using the cheats menu and destroy the 7 beach chairs for about 100k each. Once you've broken the last chair you won't have to leave the treehouse. Go into the cheats menu and choose the treehouse again and after a quick load the chairs are reset.

If you decided to not do all 25 skill points this becomes a more lengthy grind and you'll have to find other means of grinding like for example running through the Technomite City on Challax described in this link.
https://gamefaqs.gamespot.com/boards/932613-ratchet-and-clan...