As for the beast trio..
For what I have with them, it varies, if you have noticed something with them, more specifically with Renamon, they got their strength from the willpower, (I will speak more of the fox and think of the Lucario to a smaller, but close degree).
Starting with the fact that she has vast knowledge of the real and Digital World thanks to the Tamers adventures, Renamon can understand the actual situation of both worlds, she is intelligent and can can use any resource to her advantage to do the right thing. Also she has the advantages of being both a digital and biological being, something that possibly puts her in another category from most videogame characters.
To explain the last statement, the Tamers and the Digimon needed to be digital or data to merge and become the ultimate forms they had like Sakuyamon, but when they came back to the Human World, this became impossible, but thanks to a Tamer and her partner Dobbermon (wow.. such creativity there..) they became hybrids of both sides, giving them the pros of being both biological and digital beings and protecting them from most, if not all cons. (You can`t infect a person with a computer virus or can poison data with Malaria)
So with this advantage, Renamon trained while traveling to different Worlds, learning new things, meeting new people and so on until meeting Nera in the Pokèmon World. The Lucario and Forslass actually share the hybrid thing with the Digimon because of their souls being connected to the fox, so when they were ressurrected, they became similar to the golden Kitsune.
Obviously they can be damaged, losing limbs and causing mortal wounds can kill them, but then again comes the Willpower, if some of you remember the base 3 assault, Renamon was actually shot on the chest, it did put her to extreme danger since the bullet passed through her, yet she still lives, the reason for this is still something I can`t reveal, but has been hinted throughout both season 1 and 2 of ATWAG, mostly with the release of the D-Reaper.
Willpower is a key element on the vixen as it is also with living beings, if you have low willpower and/or self esteem, you would be weak minded and have no drive, Renamon is the opposite of this, albeit she is all that calm and focused Digimon, she has the drive to live and enjoy new things, and she will do anything to help others. With this, the fox will keep fighting until her last breath and still keep trying, in simple words.. SHE won`t give up.
Now to how high Renamon, Nera, and Mara`s capabilities actually are. They have way a lot of energy reserves (take the fox`s Miko mode and her healing marathon through Gensokyo), Incredible strength (The Lucario managing to lifting a Wailord with ease) and enduring devastating attacks (Mara receiving Dark John`s enraged energy charged sphere, and many others).
They all have great abilities that could actually be OP if they went to that level of strength, such thing would need their combined abilities to do so (I got something ready for such event, think of Gogeta in Super Saiyan 4 mode, because I got an image for it) with this thing, they would be next to invincible, (I will obviously put some rules on it), but we will talk about this later, or if you want to, PM me, I can tell you without problem :P
Back on track, their abilities(as you people have seen) vary depending on the situation, sometimes they can be used for speed, strength, intelligence, and so on with where they spend their energy, Nera would be able to sense anything in any direction, in any way, with the smallest thing, Mara would be able to hit something with absolute zero temperature in varying ranges from a room, to a whole city and Renamon could be as fast as ludicrous speed or as intelligent to have a good chess match with Patchouli or that character S121 mentioned to be a genious in his massive arc. And those are some things they could do if put into the needed scenarios.
At the moment, the trio can give the original Masterchief (seriously) a serious battle, winning or losing is debatable, but don`t think it is an easy bet at all, it is a hard one. But then again, if they are put in a scenario, they won`t hesitate to give their all.
I probably have missed many things, that is why you have the right to ask Utsuh.

