I think the main problem with your team is that some of your monsters aren’t all that good and outclassed by better monsters.
Searex is bad.
Metalodious and Goldenhorn are fine the way they are now. Nilomoth I feel that should be placed near the middle or back of the lineup but not in the first three as its too slow and easily outsped by many. Consider getting a faster monster.
Fireheart is decent but you could probably try to put it after pyroviper so that it can hit harder with ally flame, but I think you should try to replace Fireheart with pyrowyrm or better yet magmawyrm as they are both better fire monsters.
Georex and raptorex I suppose could be useful in the lower leagues but not in master league plus the nine star wyrms are generally better than them and sadly enough even they arent all that good in master league. For now though I would suggest going for the hatchlings and getting their evolve forms and use those instead.
Leviathan can be fused with cherubion to make angelon which is a much better monster than leviathan.
Try using a monster like Raioh or Stormfox or Raijin or some other monster(s) that can stun before Voltiger so that Voltiger can make better use of its timestrike ability.
Glazio is bad also. Penguini is much better at the very end than Glazio. Justbe sure that at least the two arks before Penguini are able to self sacrifice themselves so that penguini can have a chance to showdown. Anubis would be a decent monster to use before penguini as it can protect penguini with guardian while sacrficing itself to heal penguini with offering though there are better options.
Thats pretty much it. Otherwise its best to just leave pvp alone for a while and get better monsters. The nine star wyrms, pyrowyrm, ventowyrm, hydrowyrm (which you already have), and gaiawyrm are pretty strong in lower leagues though later on in higher leagues against stronger players, they arent all that good and so you would want to invest in a typhon, magma, and omegawyrm. Other monsters like chopperbug, gremknight, halopard, raioh, stormfox, raijin, and barricadus are good options to help support your other monsters. Based on your team you posted, it seems like you are just going with brute force, which isnt gong to get you far. I find that even knighthawk could be a good support but is a harder to use safely and properly than the others I listed so you probably might not like the hawk.
Finally if you go to the pvp section of the forums, in one of the pinned topics, there is a list of various teams and strategies that you could try out.