Firstly, you can stop searching such a Ditto because nobody got one even close to that.
Furthermore, there is no use of a 5 IVs + nature ditto unless you want to breed a 6 IVs nature comp but in this case you say that it's for an adamant Metagross so you need only 5 IVs, then, you must looking for a 4 IVs + nature Ditto, very rare but realistic.
Good luck in your quest !