The events rotate so soon or later they will be up again. We will get a special one at thursdays, that we will be able to trade for specific mega shards, including HKabuterimon. On jp version every week have new events and they stay up for 2 weeks like here on DH. Remember that you only need to farm lots of shards for the +4 awakening.
Max your MEtemon friendship on Normal quests that use 2 stamina, you have a great potential mon since is a +2 already. No need to max lv. I researched mine and it turned into a Poyomon, so will be Otamamon/Gomamon/Betamon as rookie giving lots of options to evolve - no need to evolve into another MEtemon.
Keep 3 megas all time, one with AoE skill for help farming. When you get more of then start to research - feel free to evolve a MGaruru and a SaberLeo, you get a WGaruru and a GrapLeo finishing the Beginner Quests if you don't have good mons to evolve into then.
Your WarGreys: save your best with AoE skill for farming purposes. The others use as base for research or fodder for another mon to awaken when you can.
Your other mons evolve to Champion and max lv - wait for thursday to see what megas se will be vale to get together with HKabuterimon.
And save a slot on farm for research - the link points mons always use for fodder.