>>55667273>>55667313mewtwo isn't a pokemon that wins matchups or generates switch advantage. Hell ML in general is rarely a meta where switch is important. What mewtwo does is pressure shields from opponents and has nearly no bad matchup
You can see here that one psystrike from mewtwo does a fair amount of damage, and Dialga Origin can't farm mewtwo down before it gets to two more psystrikes so it's forced to Iron head at some point. Now Dialga can Iron head immediately but that just means it'll get reverse farmed and probably wont even get to a second move. They'll throw the iron head before you get to a second Psystrike (and yes you throw psystrike vs Dialga) which means you can now dictate the matchup. If you shield the Iron head dialga is not getting to a second move vs Shadow Mewtwo before DB's ko, but also mewtwo will get two more psystrikes before it's taken out (IV dependant) and will force two shields if the Dialga player wants to keep switch.